Question

In an AP , if the common difference (d)=-4,and the seventh term (a7) is 4 ,then find the first term.

Answer 1

a7=4
d=-4
a+6d=a7
a+6×-4=4
a-24=4
a=28

Answer 2

First term of the AP = 28

Step-by-step explanation:

Given data:

Common difference (d) = –4

Seventh term ($a_7$) = 4

General formula to find nth term of AP:

$a_n=a_1+(n-1)d$

$a_7=a_1+(7-1)(-4)$

$4=a_1+(6)(-4)$

$4=a_1-24$

$4+24=a_1$

$28=a_1$

$a_1=28$

First term of the AP = 28.

To learn more...

1. In an AP,if the common difference (d)=-4,and the seventh term (a7)is 4, then find the first term.

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2. In an AP if common difference d = -4 and the seventh term (a7) is 4 then find the first term

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