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Ncert solutions Grade 8 Mathematics Science Chapters in NCERT Solutions - Mathematics , Class 8 Exercises in Squares and Square Roots Question 1 Q1) Find the square of the following numbers. (i) 32 (ii) 35 (iii) 86 (iv) 93 (v) 71 (vi) 46 Solution Transcript Solution: (i) \left(32\right)^2=\left(30+2\right)^2=\left(30\right)^2+2\times30\times2+\left(2\right)^2(32) 2 =(30+2) 2 =(30) 2 +2×30×2+(2) 2 [\because\left(a+b\right)^2=a^2+2ab+b^2∵(a+b) 2 =a 2 +2ab+b 2 ] = 900 + 120 + 4 = 1024 (ii) \left(35\right)^2=\left(30+5\right)^2=\left(30\right)^2+2\times30\times5+\left(5\right)^2(35) 2 =(30+5) 2 =(30) 2 +2×30×5+(5) 2 [\because\left(a+b\right)^2=a^2+2ab+b^2∵(a+b) 2 =a 2 +2ab+b 2 = 900 + 300 + 25 = 1225 (iii) \left(86\right)^2=\left(80+6\right)^2=\left(80\right)^2+2\times80\times6+\left(6\right)^2(86) 2 =(80+6) 2 =(80) 2 +2×80×6+(6) 2 [\because\left(a+b\right)^2=a^2+2ab+b^2∵(a+b) 2 =a 2 +2ab+b 2 = 8100 + 540 + 9 = 8649 (iv) \left(93\right)^2=\left(90+3\right)^2=\left(90\right)^2+2\times90\times3+\left(3\right)^2(93) 2 =(90+3) 2 =(90) 2 +2×90×3+(3) 2 [\because\left(a+b\right)^2=a^2+2ab+b^2∵(a+b) 2 =a 2 +2ab+b 2 ] = 8100 + 540 + 9 = 8649 (v) \left(71\right)^2=\left(70+1\right)^2=\left(70\right)^2+2\times70\times1+\left(1\right)^2(71) 2 =(70+1) 2 =(70) 2 +2×70×1+(1) 2 [\because\left(a+b\right)^2=a^2+2ab+b^2∵(a+b) 2 =a 2 +2ab+b 2 = 4900 + 140 + 1 = 5041 (vi) \left(46\right)^2=\left(40+6\right)^2=\left(40\right)^2+2\times40\times6+\left(6\right)^2(46) 2 =(40+6) 2 =(40) 2 +2×40×6+(6) 2 [\because\left(a+b\right)^2=a^2+2ab+b^2∵(a+b) 2 =a 2 +2ab+b 2 ] = 1600 + 480 + 36 = 2116

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Calculate the radius of curvature of an equi-concave lens of refractive index 1.5, when it is kep medium of refractive index 1.4 , to have a power of -5D ?

Posted by Manveer Singh Gaba 5 years ago (9169035)

CBSE > Class 12 > Physics

1 answers

Mr. Singh 5 years ago (5002243)

We know that the lens makers formula for a concave lens as follows :- 1/f=(miu - 1)[1/R1- 1/R2] Now, it is given that the lens is an equi-convex lens, that is therefore 1/f=[miu2/miu1 -1][1/-R -1/R] =[miu2-1/miu1][-2/R] Given, Refractive index of lens is miu2=1.5 Refractive index of medium is miu1=1.4 Power of the lens = -5D therefore, f=1/P =1/-5m. Or f=100/-5 cm = -20cm therefore 1/f =[miu2/miu1-1][-2/R] 1/-20=[1.5/1.4-1][-2/R] 1/-20=[0.1/1.4][-2/R] R=0.1/1.4 into 2 into 20 = 40/14 = 2.859 cm.

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What is question......?

Posted by Royal Thakur ? 5 years ago (9579994)

CBSE > Class 11 > Other Subjects

1 answers

Aadya Singh 5 years ago (10036809)

Kese ho? ?

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How to blend any pencil sketch with 10B pencil shade

Posted by Koushal Sharma 5 years ago (10356821)

CBSE > Class 11 > Painting

1 answers

Dipanshu Kumar 4 years, 11 months ago (10192883)

Heelp

9 Thank You

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Allô? Is there anyone who can teach m French? Si'l vois plaît

Posted by Tanu Choudhary # 5 years ago (10288810)

CBSE > Class 10 > English Language and Literature

2 answers

Secret ??? 5 years ago (10356051)

Why

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Ansh Sharma 5 years ago (9219327)

Desôle , I don't think so.

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Guys I have to write a speech on whatever topic so on what topic I should write

Posted by Tanu Choudhary # 5 years ago (10288810)

CBSE > Class 10 > English Language and Literature

2 answers

Malaika Sharma 4 years, 11 months ago (9421416)

?Famers' protest. ?Impact of lockdown on the environment. ?Online classes. ?Craze of fashion among teenagers. ?Its better to be alone than in bad company.

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Ujjawal Mittal 5 years ago (9190400)

My experience in lockdown

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976 More than 2835

Posted by Kumar Thangavel 5 years ago (10331491)

CBSE > Class 04 > Mathematics

2 answers

Brihat Guddanti 5 years ago (8915025)

976 more than 2835 = 976 + 2835 = 3811.So the answer for 976 more than 2835 is equal to 3811.

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Yogita Ingle 5 years ago (2577571)

976 more than 2835 = 976+2835 = 3811

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What is homophone ?And what is homophone of accept? Affect. Access. And bare.

Posted by Ibrahim Khalil 5 years ago (10351284)

CBSE > Class 09 > English Lang & Lit. (184)

2 answers

Ibrahim Khalil 5 years ago (10351284)

Thanks thakur

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Ayush Thakur 5 years ago (8579781)

A word that is pronounced the same as another word but that has a different spelling and meaning is known as homophones. Homophone of accept is except, affect is effect, access is excess and bare is bear.

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How many heart's chambers in cockroach..??

Posted by Ma Raikwar 5 years ago (10245361)

CBSE > Class 11 > Biology

4 answers

Mahima S 4 years, 11 months ago (9862641)

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Yogita Ingle 5 years ago (2577571)

Cockroaches are pests inhabiting the unhygienic and damp places. They are dark brown in colour belonging to the phylum Arthropoda, the Blattidae family, and class Insecta.

Cockroaches have 13 chambered hearts. 3 chambers are present in the thorax and 10 in the abdomen.

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Ma Raikwar 5 years ago (10245361)

Ok thanks

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First Name 5 years ago (10129186)

Cockroach doesn't have a heart . They have OCS (open circulatory system)

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Rip van winkle Questioa answer

Posted by Manish S Dyashetty Degry 5 years ago (10108117)

CBSE > Class 05 > English

2 answers

Shashank Namboodiri 5 years ago (10353935)

https://mycbseguide.com/blog/ncert-solutions-for-class-5-english-rip-van-winkle/

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Shashank Namboodiri 5 years ago (10353935)

https://www.freencertsolutions.com/ncert-solutions-for-class-5-english-chapter-10-rip-van-winkle/

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Samobayo hi durjoy

Posted by A Nitin 5 years ago (9224933)

CBSE > Class 07 > Sanskrit

2 answers

Rudra Chetariya 5 years ago (9575707)

what ??

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Parshant Rajput 5 years ago (10349044)

Sambi hi durjan h

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We can look for solutions on Google which can provide a wide range of answers but still we look for solutions to our friends who we don't know personally. This can be termed as human nature who gives more importance to his/her fellow beings

Posted by Tanu Choudhary # 5 years ago (10288810)

CBSE > Class 10 > Social Science

2 answers

Somashekhar H 5 years ago (9399287)

that's the point

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Rashi Dadwal 5 years ago (5069069)

Great said

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Comparative statement and common size statement solutions

Posted by Teena Sharma 5 years ago (10323567)

CBSE > Class 12 > Accountancy

0 answers

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2x + 9 = 6

Posted by Ishika Sharma 5 years ago (10338504)

CBSE > Class 09 > Mathematics

5 answers

Shivam Kumar 5 years ago (8953985)

2x+9=6 2x=6-9 2x=-3 X=-3/2

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Zaid . 5 years ago (10345176)

-3/2

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Satyam Kumar 5 years ago (10355211)

x = -3/2

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Kripa Daga 5 years ago (10187336)

-3/2

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Yogita Ingle 5 years ago (2577571)

2x + 9 = 6

2x = 6 - 9

2x = -3

x = -3/2

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If O is the centre of the circle find the value of x in the given figure

Posted by Ishika Sharma 5 years ago (10338504)

CBSE > Class 09 > Mathematics

1 answers

Ma Raikwar 5 years ago (10245361)

Where is the figure

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Prove that median of an equilateral triangle is perpendicular to the corresponding side. By coordinate plss

Posted by Garima Sharma 5 years ago (7685735)

CBSE > Class 11 > Mathematics

1 answers

First Name 5 years ago (10129186)

Use mid point formula to find the coordinates of the point where median intersects the side. Use distance formula and converse of pythagoras theorem to prove perpendicularity, or use slope

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Solve 2x+3y=11 and 2x-4y=-24 and hence find the value of m for which y=mx+3 .

Posted by Baisa Hkm ?? 5 years ago (10081109)

CBSE > Class 10 > Mathematics

5 answers

Gourav Yadav 5 years ago (9673313)

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Gourav Yadav 5 years ago (9673313)

Fbgne

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Tanu Choudhary # 5 years ago (10288810)

Hi yogita thanks for your solution I have miscalculated the value of x and m

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Tanu Choudhary # 5 years ago (10288810)

By using elimination method we can easily get y=5, x=1/3, m=6

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Yogita Ingle 5 years ago (2577571)

Given equations are

2x+3y=11−−−−(1)

2x−4y=−24−−−−(2)

Form (1)

2x+3y=11

⇒2x=11−3y

⇒x=211−3y−−−(3)

substituting x in(2)

2x−4y=−24

⇒2(211−3y)−4y=−24

⇒11−3y−4y=−24

⇒11−7y=−24

⇒7y=35

⇒y=35/7

⇒y=5.

putting y = 5 in (3)

x=[11−3(5)]/2

⇒x=[11−15]/2

⇒x=−4/2

∴x=−2.

Hence x = -2 and y = 5 is the solution of the

equation.

Now, we have to find m

y=mx+3 ∴m=−1

5=3(−2)+3

5−3=−2m⇒−2m=2

⇒m=−2/x=−1

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What is cardiac cycle ? Explain the stroke volume. Class 11

Posted by Neil Modi 5 years ago (10008913)

CBSE > Class 11 > Biology

1 answers

Yogita Ingle 5 years ago (2577571)

The sequential event in the heart which is cyclically repeated is called the cardiac cycle and it consists of systole and diastole of both the atria and ventricles.
Duration of a cardiac cycle is 0.8 seconds.
During a cardiac cycle, each ventricle pumps out approximately 70 mL of blood which is called the stroke volume.
The stroke volume multiplied by the heart rate gives the cardiac output.
Cardiac output can be defined as the volume of blood pumped out by each ventricle per minute and averages 5000 mL or 5 litres in a healthy individual.
As the tricuspid and bicuspid valves are open, blood from the pulmonary veins and vena cava flows into the left and the right ventricle respectively through the left and right atria and the semilunar valves are closed at this stage.
The SAN now generates an action potential which stimulates both the atria to undergo a simultaneous contraction – the atrial systole.
The action potential is conducted to the ventricular side by the AVN and AV bundle from where the bundle of HIS transmits it through the entire ventricular musculature, which causes the ventricular muscles to contract, (ventricular systole), the atria undergoes relaxation (diastole), coinciding with the ventricular systole.
Ventricular systole increases the ventricular pressure causing the closure of tricuspid and bicuspid valves.
As the ventricular pressure increases further, the semilunar valves guarding the pulmonary artery (right side) and the aorta (left side) are forced open, allowing the blood in the ventricles to flow through these vessels into the circulatory pathways.
The ventricles now relax (ventricular diastole) and the ventricular pressure falls causing the closure of semilunar valves which prevents the backflow of blood into the ventricles.
As the ventricular pressure declines further, the tricuspid and bicuspid valves are pushed open by the pressure in the atria exerted by the blood which was being emptied into them by the veins and the blood now once again moves freely to the ventricles, leading the ventricles and atria again in a relaxed (joint diastole) state.
Again, the SAN generates a new action potential and the events are repeated.
During each cardiac cycle two prominent sounds are produced which can be easily heard through a stethoscope.
The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves, whereas the second heart sound (dub) is associated with the closure of the semilunar valves.

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Human circulatory system is double circulating. Justify. Class 11

Posted by Neil Modi 5 years ago (10008913)

CBSE > Class 11 > Biology

1 answers

Yogita Ingle 5 years ago (2577571)

The double circulation of blood includes:
(i) Systematic Circulation
(ii) Pulmonary Circulation

Systematic Circulation

Systemic circulation transfers oxygenated blood from left ventricles to capillaries in the tissue.
The oxygen-rich blood is passed to the aorta for distribution into various body sections.
The veins and venules later absorb the deoxygenated blood which is rich in carbon dioxide from different parts of the body.
The deoxygenated blood is transferred back to the superior vena cava, then on to the right atrium.
The right atrium transports blood to the right ventricle for pulmonary circulation, after receiving the deoxygenated blood.

Pulmonary Circulation

The distribution of blood starts in the pulmonary circulation from the right atrium to the left atrium.
The pulmonary artery receives the blood from the right ventricle and carries to the lungs for oxygenation.
When the oxygenated blood is pumped back to the left atrium via the pulmonary vein, that is brought to the left ventricles, after the purification process.

It is necessary for a human being to separate oxygenated and de-oxygenated blood because this makes their circulatory system more efficient and helps in maintaining constant body temperature.

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Write detailed note on disorders of circulatory system Class 11

Posted by Neil Modi 5 years ago (10008913)

CBSE > Class 11 > Biology

1 answers

Yogita Ingle 5 years ago (2577571)

High Blood Pressure:
The pressure which is created by the blood flow on the wall of blood vessels. In humans, the normal range of blood pressure is 120/80. In this range, 120 is the systolic blood pressure and 80 is the diastolic blood pressure.

Systolic blood pressure – It is defined as the pressure that is created in the arteries when blood flows through arteries to the rest of the body when the heartbeats.

Coronary Artery Disease (CAD)Coronary artery disease is also termed as atherosclerosis. Coronary Artery Disease is the disease which is caused by the deposition of waxy substances in the blood vessels which supplies the blood to the heart muscle and this deposition leads to the blockage of the blood flow. The examples of waxy substances are fat, cholesterol and fibrous tissues. As a result, it may also cause a heart attack.

Angina
Angina is the condition in which chest pain occurs if the heart receives insufficient oxygen and nutrients through the blood vessels. Angina could be caused by the different risk factors. These factors are as follows:
Smoking.
Age factor (More than 40 age).
Hypertension.
Obesity.
Physical inactivity.

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How does human heart activity monitored? Explain with P,Q,R,S and T wave complex Class 11

Posted by Neil Modi 5 years ago (10008913)

CBSE > Class 11 > Biology

1 answers

Meghna Thapar 4 years, 11 months ago (6237)

The P wave indicates atrial depolarization. The P wave occurs when the sinus node, also known as the sinoatrial node, creates an action potential that depolarizes the atria. The P wave should be upright in lead II if the action potential is originating from the SA node. ECG – A Pictorial Primer. Atrial and ventricular depolarization and repolarization are represented on the ECG as a series of waves: the P wave followed by the QRS complex and the T wave. The first deflection is the P wave associated with right and left atrial depolarization. ... The second wave is the QRS complex.

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Sunita apna sara kaam khud karti thi jaise kapde badalna , jute pahnna, aadi niche darshay gay chitron ko dekh kar likhiye ki unme koun koun se kaam (kiryaye) ho rahe hain

Posted by [email protected] Malik 5 years ago (10356540)

CBSE > Class 04 > हिंदी

2 answers

Aayat Khan 4 years, 11 months ago (9914657)

पाठ ‌‌ २ का मुझ पूर workचईए

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[email protected] Malik 5 years ago (10356540)

Pls hame iska answer de dijiye

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What is meant by origin of heart beats ? Explain the conducting system of heart beats Class 11

Posted by Neil Modi 5 years ago (10008913)

CBSE > Class 11 > Biology

1 answers

Yogita Ingle 5 years ago (2577571)

Heartbeat is triggered by electrical impulses which is induced by a specific pathway. The SA node known as sinoatrial node is the heart’s natural pacemaker. This impulse begins in this small bundle of specialized cells which is located in the right atrium. The electrical impulse spreads through the walls of the atria and it causes contraction. Contraction sends the blood into the ventricles.

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