Math, asked by sarthakrahate24, 11 months ago

the sum of seventh and eighth term of AP is 4 x + 7 and the 11 term is 2 x + 5 find the first and the common difference of ap for x is equal to 1

Answers

Answered by cheruku1973
1

Step-by-step explanation:

seventh term= a+6d

eighth term=a+7d

a+6d+a+7d = 4x +7

2a+13d=4x+7

given x=1

2a+ 13d=11

a=11-13d/2

eleventh term = 2x+5

a+10d=7

11-13d/2+10d=7

11-13d+20d=14

11+7d=14

7d=3

d=3/7

a=11-13(3/7)/2

=11-39/14

=154-39/14

=115/9

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