Question

In A.P d=2,t20=49,a=?

Answer 1

$t20 = a + (20 - 1) \times 2 \\ 49 = a + 19 \times 2 \\ 49 = a + 38 \\ 49 - 38 = a \\ a = 11$

Answer 2

a = ?

T20 = 49

d = 2

=> T20 = a + (20-1)d

=> 49 = a + 38

=> a = 49 - 38

=> $\fbox{a = 11}$