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  • 1 answers

Gaurav Seth 5 years, 1 month ago

1. Find the roots of the following quadratic equations, if they exist, by the method of completing the square:

(i) 2x2 – 7x +3 = 0

(ii) 2x2 + x – 4 = 0
(iii) 4x2 + 4√3x + 3 = 0

(iv) 2x2 + x + 4 = 0

Solutions:

(i) 2x2 – 7x + 3 = 0

⇒ 2x2 – 7= – 3

Dividing by 2 on both sides, we get

⇒ x2 -7x/2 = -3/2

⇒ x-2 × x ×7/4 = -3/2

On adding (7/4)2 to both sides of equation, we get

⇒ (x)2-2×x×7/4 +(7/4)2 = (7/4)2-3/2

⇒ (x-7/4)2 = (49/16) – (3/2)

⇒(x-7/4)= 25/16

⇒(x-7/4)2 = ±5/4

⇒ x = 7/4 ± 5/4

⇒ x = 7/4 + 5/4 or x = 7/4 – 5/4

⇒ x = 12/4 or x = 2/4

⇒ x = 3 or x = 1/2

(ii) 2x2 + x – 4 = 0

⇒ 2x2 + x = 4

Dividing both sides of the equation by 2, we get

⇒ x2 +x/2 = 2

Now on adding (1/4)to both sides of the equation, we get,

⇒ (x)+ 2 × x × 1/4 + (1/4)2 = 2 + (1/4)2

⇒ (x + 1/4)2 = 33/16

⇒ x + 1/4 = ± √33/4

⇒ x = ± √33/4 – 1/4

⇒ x = ± √33-1/4

Therefore, either x = √33-1/4 or x = -√33-1/4

(iii) 4x2 + 4√3x + 3 = 0

Converting the equation into a2+2ab+bform, we get,

⇒ (2x)2 + 2 × 2x × √3 + (√3)2 = 0

⇒ (2x + √3)2 = 0

⇒ (2x + √3) = 0 and (2x + √3) = 0

Therefore, either x = -√3/2 or x = -√3/2.

(iv) 2x2 + x + 4 = 0

⇒ 2x2 + x = -4

Dividing both sides of the equation by 2, we get

⇒ x2 + 1/2x = 2

⇒ x2 + 2 × x × 1/4 = -2

By adding (1/4)to both sides of the equation, we get

⇒ (x)+ 2 × x × 1/4 + (1/4)2 = (1/4)– 2

⇒ (x + 1/4)2 = 1/16 – 2

⇒ (x + 1/4)2 = -31/16

As we know, the square of numbers cannot be negative.

Therefore, there is no real root for the given equation, 2x2 + x + 4 = 0.

  • 2 answers

Parul Ailawadi 5 years, 1 month ago

LCM×HCF=Product of two numbers LCM×9=306×657 LCM×9=201042 LCM=201042÷9 LCM=22338

Anuj Mathpal 5 years, 1 month ago

Let the LCM = x. HCF *LCM =Product of two numbers. 9*x=306*657 x=306*657/9 x=34*657 x=22,338
  • 1 answers

Gaurav Seth 5 years ago

Let AB be a diameter of the circle. Two tangents PQ and RS are drawn at points A and B respectively.

Radius drawn to these tangents will be perpendicular to the tangents.

Thus, OA ⊥ RS and OB ⊥ PQ

∠OAR = 90º

∠OAS = 90º

∠OBP = 90º

∠OBQ = 90º

It can be observed that

∠OAR = ∠OBQ (Alternate interior angles)

∠OAS = ∠OBP (Alternate interior angles)

Since alternate interior angles are equal, lines PQ and RS will be parallel.

  • 3 answers

Sourav Keshri 5 years, 1 month ago

A=(-1, 7) B=(4, -3) Ratio=2:3 Let the coordinate point P(x, y) P(x, y) =(m1x2+m2x1/m1+m2, m1y2+m2y1/m1+m2) P(x, y) ={2×4+3×(-1) /2+3, 2×(-3) +3×7/2+3} P(x, y) =(8-3/5, -6+21/5) P(x, y) =(5/5,15/5) P(x, y) =(1, 3) Hence, coordinate point are P(1, 3)

Parul . 5 years, 1 month ago

A=(-1, 7) B=(4, -3) Ratio=2:3 Let the coordinate point P(x, y) P(x, y) =(m1x2+m2x1/m1+m2, m1y2+m2y1/m1+m2) P(x, y) ={2×4+3×(-1) /2+3, 2×(-3) +3×7/2+3} P(x, y) =(8-3/5, -6+21/5) P(x, y) =(5/5,15/5) P(x, y) =(1, 3) Hence, coordinate point are P(1, 3)

A K47 5 years, 1 month ago

(1,3) is the dividing point
  • 1 answers

Gaurav Seth 5 years ago

Given, 
Power of lens, P = - 2 D

Therefore,

Focal length,  
f = 1 / P

= 1 / 2 m = - 0.5 
The negative sign of focal length indicates that the lens is concave.

 

Given f = - 20 cm, (sign convention) , v = - 10 cm

(∴ image formed by concave lens is virtual)

By using lens formula, 

or u = - 20 

Thus the object is placed at 20 cm from the concave lens  

  • 1 answers

Siddharth Chouhan 5 years, 1 month ago

What is the formula of class mark
  • 2 answers

Parul Ailawadi 5 years, 1 month ago

Linear equation

Gaurav Seth 5 years, 1 month ago

The equation whose graph is a straight line is called linear equation.

Linear equations are also first-degree equations as it has the highest exponent of variables as 1.  Some of the examples of such equations are as follows:

  • 2x – 3 = 0, 
  • 2y = 8
  •  m + 1 = 0,
  •  x/2 = 3
  • 1 answers

Gaurav Seth 5 years, 1 month ago

Both assumed mean method and step deviation method are ways to find mean without any complications...

step deviation method is just an elaboration of assumed mean.

1. Assumed Mean method:

Step 1- Tabulate the continuous class intervals and frequency alongwith class marks.

  Class Mark = Upper Limit + Lower Limit

                                            2

Step 2- Assume any of the class marks to be your  mean .

Step 3- Take out the differences of the assumed mean and class marks.{ xi - a = di}

Example if the class marks are 20, 30,40,50,60,70 and so on......and if the a =50 then,di is -30,-20,-10,0,10,20and so on.....

Step 4: Multiply fand di .

Step5:  

  d  = sum of fidi

  sum of fi

Step 6:  Mean = a + d

  • 1 answers

Anuj Mathpal 5 years, 1 month ago

Yes 50%? you are right
  • 1 answers

Gaurav Seth 5 years, 1 month ago

Q : The length of the hypotenuse of a right triangle exceeds the length of its base by 2 cm and exceeds twice the length of altitude by 1 cm. Find the length of each side of the triangle.

S o l u t i o n:

Let altitude of triangle be x.

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  • 1 answers

Gaurav Seth 5 years ago

TEP DEVIATION METHOD:

Step deviation method is used in the cases where the deviation from the assumed mean 'A' are multiples of a common number. If the values of ‘di’ for each class is a multiple of ‘h’ the calculation become simpler by taking ui= di/h = (xi - A )/h

Here, h is the class size of each class interval.

★★ Find the class marks of class interval. These class marks would serve as the representative of whole class and are represented by xi.  

★★ Class marks (xi)  = ( lower limit + upper limit) /2

★★ We may take Assumed mean 'A’ to be that xi which lies in the middle of x1 ,x2 …..xn

MEAN = A + h ×(Σfiui /Σfi) , where ui =  (xi - A )/h

[‘Σ’ Sigma means ‘summation’ ]

FREQUENCY DISTRIBUTION TABLE

★★ Here,the frequency table is given in inclusive form. So we first change it into exclusive form by  subtracting and adding h/2 to the lower and upper limits respectively of each class ,where ‘h’ denotes the difference of lower limit of a class and upper limit of the previous class.

Here, h/2 = ½ = 0.5  

 

From the table : Σfiui = 25 ,  Σfi = 400

Let the assumed mean, A = 57,  h = 3

MEAN = A + h ×(Σfiui /Σfi)

Mean = 57 + 3 (25/400)

= 57 + 3 (1/16)

= 57 + 3/16

= 57 + 0.187

= 57.187

Mean = 57.19  (approximate)

Hence, the Mean number of mangoes kept in a packing box is 57.19  (approximate)

  • 1 answers

Rîtíkã Çhäûhāñ 5 years, 1 month ago

R.E.F image In △ PQR using pythagoras theorem (PR) 2 =(PQ) 2 +(QR) 2 625-49=(QR) 2 (QR) 2 =576 QR=24CM now tan P = 7 24 ​ and tan R = 24 7 ​ tanP-tanR= 7 24 ​ − 24 7 ​ = 168 576−49 ​ = 168 527 ​ solution
  • 1 answers

Moin Uddin 5 years, 1 month ago

X1 = 2. X2= 5 Y1 = 3. Y2 = 7 Distance fromula, Distance = √(X2 - X1)² +( Y2- Y1 )² = √(5-2)² + (7-3)² =√3² + 4² =√9+16 =√25 =5 unit. Ans
  • 1 answers

Vijender Choudhary 5 years, 1 month ago

Let the cost of bat be =x And the cost of ball be =y A.T.Q 7x+3y=3800 (1) A.T.Q 3x+5y=1750 (2) Now solve this equation by elimination method
  • 2 answers

Rîtíkã Çhäûhāñ 5 years, 1 month ago

If any digit has the last digit 10 that means it divisible by 10. The factor of 10=2×5, So value of 6 n should be divisible by 2 and 5. Both 6 n is divisible by 2 but not divisible by 5. So, it can not end with 0.

Moin Uddin 5 years, 1 month ago

Yes, 6n can end with 0 . When we put n= 5 ( because n is any natural no.) Therefore 6*5= 30 which ends with 0. Thus, 6n can end with 0
  • 2 answers

Rîtíkã Çhäûhāñ 5 years, 1 month ago

Dividend =p(x)=x 3 −3x 2 +x+2 Quotient =q(x)=x−2 Remainder =r(x)=2x+4 By division algorithm, p(x)=q(x)g(x)+r(x) ⇒g(x)= q(x) p(x)−r(x) ​ ⇒g(x)= x−2 x 3 −3x 2 +x+2+2x−4 ​ ⇒g(x)= x−2 x 3 −3x 2 +3x−2 ​ So, g(x)=x 2 −x+1 solution

Gaurav Seth 5 years, 1 month ago

Answer:

g(x) = x² - x + 1

Step-by-step explanation:

On dividing x3-3x2+x+2 by a polynomial g(x),the quotient and remainder were x-2 and -2x+4 respectively.find g(x)

 

f(x) = x³ - 3x² + x + 2

q(x) = x - 2

let say

g(x) = ax² + bx + c

r = - 2x + 4

f(x)  = g(x)q(x) + r

=> x³ - 3x² + x + 2 = (ax² + bx + c)(x - 2) + (-2x + 4)

=> x³ - 3x² + x + 2 =  ax³ + x²(b - 2a) + x(c - 2b) -2c -2x + 4

=> x³ - 3x² + x + 2 =  ax³ + x²(b - 2a) + x(c - 2b - 2)  + (-2c  + 4)

Equating Power terms

a = 1

b - 2a = - 3  => b -2 = -3 => b = -1

c - 2b - 2 = 1 => c + 2 - 2 = 1  => c = 1

or -2c  + 4 = 2  => -2c = -2 => c = 1

 

g(x) = x² - x + 1

  • 2 answers

Rîtíkã Çhäûhāñ 5 years, 1 month ago

A quadratic equation is written in the form a x 2 + b x + c = 0 Always change to this form first The discriminant is Δ = b 2 − 4 a c The solutions to an equation are called the 'roots' and are referred to as α and β The value of Δ tells us about the nature of the roots. If Δ > 0 ⇒ the roots are real and unequal (2 distinct roots) If Δ > 0 and a prefect square ⇒ the roots are real, unequal and ... ... ... ... ... ... ... ... ... ... ... . ... ... ... ... ... . . rational If Δ = 0 ⇒ the roots are real and equal (1 root) If Δ < 0 ⇒ the roots are imaginary and unequal Note that if a or b are irrational, the roots will be irrational. − 3 x 2 + 9 x = 4 ⇒ 3 x 2 − 9 x + 4 = 0 Δ = b 2 − 4 a c Δ = ( − 9 ) 2 − 4 ( 3 ) ( 4 ) = 33 33 > 0 and is not a perfect square Therefore, there are two roots which will be real and unequal.

A K47 5 years, 1 month ago

-159 by b² - 4ac
  • 3 answers

Saroj Yadav 5 years, 1 month ago

64 =2×2×2×2×2×2

Seenu B 5 years, 1 month ago

64=2×4×4×2

Yogita Ingle 5 years, 1 month ago

64 = 2 × 2 × 2 × 2 × 2 × 2

  • 1 answers

Yogita Ingle 5 years, 1 month ago

The given sequence is an A.P. with first term a=3 and common difference d=3. Let there be n terms in the given sequence. Then,

nth term=111

a+(n−1)d=111

3+(n−1)×3=111

n=37

Thus, the given sequence contains 37 terms.

  • 3 answers

Mohit Parmar 5 years, 1 month ago

64

Rani Kumari 5 years, 1 month ago

The equation will have unique solution for all number except 8/3

Yogita Ingle 5 years, 1 month ago

» 2x + 3y + 5 = 0

» kx + 4y = 10

➡ kx + 4y - 10 = 0

we have to find the value of k such that the pair of equations have unique solution.

we know that, when pair of equations have unique solution,

a1/a2 ≠ b1/b2

➡ 2/k ≠ 3/5

just put any value of k so that it doesn't get equal to 3/5.

you can put 1, 2 etc.

for example, k is 2, then a1/a2 = 2/2 = 1

LHS ≠ RHS

  • 1 answers

Spoorti Shrinivas 5 years, 1 month ago

2x^2 + x - 4 = 0 x = -b +\- √b^2 - 4ac _____________________ 2a x = -1 +\- √1^2 - 4*2*4 ____________________ 2*2 x = -1 +\- √1-32 _______________ 4 x = -1 +\- √31 ___________ 4 Therefore : x = -1 + √31 x= -1 - √31 _________ ________ 4 4
  • 5 answers

Saurav Bhardwaj 5 years, 1 month ago

24

Seenu B 5 years, 1 month ago

24

Tanveer Kaur 5 years, 1 month ago

24

Navnoor Singh 5 years, 1 month ago

24

Shreya The Great ??????? 5 years, 1 month ago

24
  • 1 answers

Yogita Ingle 5 years, 1 month ago

Let the three numbers in AP be a-d, a, a+d

Then, 

sum = a-d+a+a+d=15

3a = 15

So, a = 5

Also, Sum of squares = 83

(a-d)2+a2+(a+d)2=83

(5-d)2+25+(5+d)2=83

25+d2-10d+25+25+d2+10d=83

75+2d2=83

2d2=8

d=+2 or -2

When d = 2,

The numbers are 3, 5, 7

When d = -2,

The numbers are 7, 5, 3

  • 2 answers

Navnoor Singh 5 years, 1 month ago

476

Yogita Ingle 5 years, 1 month ago

Let the selling price (S. P.) be x.

 

Hence, selling price is ₹ 476.

  • 3 answers

Karan Chauhan 5 years, 1 month ago

The answer is 960

Yogita Ingle 5 years, 1 month ago

The first 8 multiples of 8 are
8, 16, 24, 32, 40, 48, 56,64
These are in an A.P., having first term as 8 and common difference as 8.
Therefore, a = 8
d = 8
S15 = ?
Sn = n/2 [2a + (n - 1)d]
S15 = 15/2 [2(8) + (15 - 1)8]
= 15/2[6 + (14) (8)]
= 15/2[16 + 112]
= 15(128)/2
= 15 × 64
= 960 

Venkataramana Shenoy 5 years, 1 month ago

The answer is 960

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