Math, asked by himanshsingh201, 1 year ago

The sum of first and 5th term of an ascending ap is 26 and product of 2nd and 4th term is 160. Find sum of first 7 terms of a.p

Answers

Answered by fazailcheema
2

a+a+4d=26

a+2d=13

a=13-2d equa1

(a+d)*(a+3d)=160 equa2

(13-2d+d)*(13- 2d + 3d ) =160

(13-d) * (13+d)=160

169-d^ 2 = 160

d=3

  • putting in equa 1

a = 13- 2 (3)

a= 13-6

a=7

  • sum of first 7 terms  

S7 = n/2{2a+ (n-1) d}  

=> 7/2(14 + 6(3))

=> 3.5(32)

=>112 answer




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