Question

the sum of third and seven term of an A.P is 6 and their product is 8 find the first term and common difference

Answer 1

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»a3+a7=6

a+2d+a+6d=6

2a+8d=6

2(a+4d)=6

a+4d=3

a=3-4d

»a3×a7=8

(a+2d)(a+7d)=8

replacing value of a"

(3-4d+2d)(3-4d+7d)=8

(3-2d)(3+3d)=8

3(3+3d)-2d(3+3d)=8

9+9d-6d-6d²=8

(9-8)+3d-6d²=0

-6d²+3d+1=0