Question

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

Answer 1

d=-4
a7=4
》a+(7-1)(-4)=4
》a+(-24)=4
》a=4+24
》a=28.
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Answer 2

✨✔️Question: In an AP, if the common difference is (-4) and seventh term is 4, then find the first term.

$\boxed{(a)n \:= \:a + \:( n-1 )\: * \:d}$

✔️✔️Answer:

Let us take n = 7
Therefore; (a)n => (a)7

Given that,
d = (-4)
(a)7 = 4

$(a)7 \: = \: a \: + \: (n - 1) \: \times d$

$4 \: = \: a \: + \: (7 - 1) \: \times \: ( - 4)$

$4 \: = \: a \: + \: ( - 24)$

$4 \: + \: 24 \: = \: a$

Therefore, a = 28.

First Term of the AP is 28.

✨✔️HOPE IT HELPS YOU....
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