The sun 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
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- a+a+4d=26
2a+4d=26
a=13-2d equa 1
- (a+d)*(a+3d)=160 equa 2
a,a+d,a+2d,a+3d, a+ 4d,a+ 5d,a+6d=?
- putting this value in equa 2
(13-2d+d)*(13-2d+3d)=160
(13-d)*(13+d)=160
13^2-d^2 =160
d=3
- putting in equa1
a=13-2(3)
a=13-6
a=7
a, a+ d, a+ 2d, a+ 3d, a+ 4d, a+ 5d , a+6d = ?
sum of first 7 terms:
7+7+3+7+6+7+9+7+12+7+15+7+18=112
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