Question

3] for an AP if tn = 4, n=7, d=-4 find a.​

Answer 1

Answer:

a-28

Step-by-step explanation:

We know, an=a+(n−1)d

Putting the value given, we get

4=a+(7−1)(−4)  or  a=4+24

⟹a=28

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Answer 2

Given,

$\rm t_n = 4 \\ \rm n = 7 \\ \rm d = - 4$

We know,

$\rm \: t_n = a + ( n- 1)d \\ \\ \tt 4 = a + \{ (7 - 1)( - 4) \} \\ \\ \tt a = 4 - \{ (7 - 1)( - 4) \} \\ \\ \tt a = 4 - \{ ( 6 )( - 4) \} \\ \\ \tt a = 4 -( - 24) \\ \\ \tt a = 4 + 24 \\ \sf a = \red{28}$