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  • 1 answers

Gaurav Seth 5 years ago

Given AP is 1,4,7,10,.....

 

In given AP first term a=1, common difference d=3

 

Since, Sn= n/2[2a+(n−1)d] ....... sum of n terms

 

Put n=20 for sum of first 20 terms

 

S20=20/2 [2(1)+(20−1)3]

 

S20=10[2+57]

 

S20=590

  • 1 answers

Yogita Ingle 5 years, 1 month ago

Sum of first 5 multiples of 3:
Sum of an AP is: n/2 ​× (2a+(n−1)d)
a=3,d=3,n=5
Then, 
Sum = 5/2 ×(2×3+(5−1)×(3))
= 5/2 ​×(6+12)

= 5/2 ×18

= 5 ×9
= 45

  • 1 answers

Gaurav Seth 5 years ago

let a = first term and d=common difference.

According to question,

7a7 = 11 a11

=>7(a+6d) = 11(a+10d)

=> 7a-11a = 110d-42d

=> -4a = 68d

=>a = -17d  ......(1)

Now , a18 = a +17d 

but a = -17 d  ..by (1)

so put this value , we get,

a18=-17d +17d =0 

Hence proved

  • 1 answers

Yogita Ingle 5 years, 1 month ago

a = 1 d = 4-1 = 3

an = a + (n-1)d

a10 = 1 + (10-1)3

a10 = 1 + (9)3

a10= 1 + 27

a10= 28

  • 1 answers

Gaurav Seth 5 years ago

When a, b, and c are real numbers, a ≠ 0 and the discriminant is zero, then the roots α and β of the quadratic equation ax2+ bx + c = 0 are real and equal.

  • 2 answers

Confusion ??? Master ??? 5 years, 1 month ago

False

Yogita Ingle 5 years, 1 month ago

A quadratic polynomial has maximum three zeroes.

False, A quadratic polynomial has two zeroes.

  • 2 answers

Confusion ??? Master ??? 5 years, 1 month ago

True

Yogita Ingle 5 years, 1 month ago

If b2 - 4ac = 0 then the roots will be a real number because b and a are real.

  • 1 answers

Yogita Ingle 5 years, 1 month ago

  (cosecA-cotA)  (cosecA+cotA)

= cosec2 A - Cot2A

= cot2A + 1 - Cot2A    (cot2A + 1 = cosec2A)

= 1

  • 1 answers

Yogita Ingle 5 years, 1 month ago

If sino = 3/5
Then, opposite side of the right angled triangle containing angle o = 3  and hypotenuse =5
Using pythagoras theorem, we get the adjacent side = 4
 
Now we have,  coso =Adjacent​/Hypotenuse=4/5 ​
And cot o =Adjacent/Opposite​= 3/4

3 cot o =3( 3/4) = 9/4

  • 5 answers
Mai buk

Bharat Kumar 5 years, 1 month ago

Serious mt lena majak kr rha tha

Bharat Kumar 5 years, 1 month ago

Hii guys to ghr ke kaam kr lo alsi logo

Akhya Sahay 5 years, 1 month ago

Me...

Ambika Ambika 5 years, 1 month ago

Hii mai bor ho raye hoo ghar per bhyte bhyte ????
  • 0 answers
  • 1 answers

Kaivalya Kumar 5 years, 1 month ago

X = (8/5) - 15 X = 1.6 - 15 X = -13.4
  • 1 answers

Yogita Ingle 5 years, 1 month ago

7429           = 17 x 19  x 23           =17 x 19 x 23

  • 1 answers

Gaurav Seth 5 years, 1 month ago

a = - 1.25, d = - 0.25

Let the series be a1, a2, a3, a4 …

a1 = a = - 1.25

a2 = a1 + d = - 1.25 - 0.25 = - 1.50

a3 = a2 + d = - 1.50 - 0.25 = - 1.75

a4 = a3 + d = - 1.75 - 0.25 = - 2.00

Clearly, the series will be 1.25, - 1.50, - 1.75, - 2.00 ……..

First four terms of this A.P. will be - 1.25, - 1.50, - 1.75 and - 2.00.

  • 1 answers

Sonika Sakhare 5 years, 1 month ago

11
  • 2 answers

Ambika Ambika 5 years, 1 month ago

You can see the page number. the page number is (12)

Ambika Ambika 5 years, 1 month ago

√2,√3,√15, π, _√2/√3, 0.10110111011110...., etc
  • 1 answers

Yogita Ingle 5 years, 1 month ago

 △ABC ~ △DEF

a(△ABC)/a( △DEF) = AB2 /DE2

 64/144 =42/DE2

8/12 = 4/DE

8DE = 48

DE = 48/8 = 6 unit

 

  • 1 answers

Yogita Ingle 5 years, 1 month ago

  tan (A+10) = 1

we know that tan 45 = 1

So, tan (A+ 10) = tan45

A + 10 = 45

A = 45 - 10

A = 35

  • 1 answers

Gaurav Seth 5 years, 1 month ago

 

Q: Prove that in a triangle, if square of one side is equal to the sum of the squares of the other two sides, then the angle opposite the first side is a right angle.

A n s w e r :

Given: A triangle ABC in which AC2 = AB2 + BC2.
To Prove: ∠B = 90°.
Construction: We construct a ΔPQR right-angled at Q such that
PQ = AB and QR = BC
Proof: Now, from ΔPQR, we have,

Now, in ΔABC and ΔPQR,

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  • 2 answers

Yogita Ingle 5 years, 1 month ago

Given, a=5,d=3,an​=50
⇒a+(n−1)d=50
⇒5+(n−1)3=50
⇒5+3n−3=50⇒3n=48⇒n=16
∴S16​=16/2​[2a+(16−1)d]=8[2×5+15×3]=440
Hence, n=16,S16​=440

Kiran Kaintura 5 years, 1 month ago

añ=a+(n-1)d 50=5+(n-1) 3 50=5+3n-3 50=2+3n 50-2=3n 48=3n 48/3=n 16=n Sn=n/2(a+añ) Sn=16/2(5+50) Sn=8(55) Sn=440
  • 1 answers
Converse of Basic Proportionality Theorem is if a line divides the any two sides of a triangle in the same ratio, then the line must be parallel to the third side... hope it would be helpful?✌
  • 2 answers

........ ...... 5 years, 1 month ago

x+y=15........(i) x-y=5.........(ii), From equation (ii), we get x=5+y Put the value of x in equation (i),we get 5+y+y=15 2y=15-5 y=10/2=5 Now, put the value of y in equation (ii), we get x-5=5 x=5+5=10 :.x=10 and y=5

Aditya Khohwal 5 years, 1 month ago

Adding by eliminTion method =2x=20 X=10 Putting in 1 eq x+y=15 Y=15-10 = 5
  • 0 answers

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