Question

In an AP if the common difference is -4 and the seventh term is 4 , then whats the first term

Answer 1

Heya !!

Common difference , d = –4

As we know, an = a+(n–1)d

Seventh term , a7 = a + (7–1) –4
=> 4 = a + 6(–4)
=> 4 = a –24
=> a = 24 + 4
=> a = 28

Answer 2

Hi friend, Harish here.

Here is your answer:

Given that,

1) Common difference of AP (d) = -4.

2) Seventh term of the AP = 4.

To find,

The first term of the AP.

Solution,

We know that,

$S_7 =(a+6d)$

⇒  $4 = a + 6\times (-4)$

⇒  $4 = a - 24$

⇒  [tex]a = 24 + 4 = 28. [/tex]

Therefore the first term of the AP is 28.
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Hope my answer is helpful to you.