Question

find a and d for the AP whose nth term is 3+4n.​

Answer 1

an = 3 + 4n

a1 = 3 + 4×1 = 7

a2 = 3 + 4×2 = 11

a3 = 3 + 4 × 3 = 15

so,

a = 7 (first term)

d = 11-7 = 15-11

d = 4

Answer 2

an=3+4n

let n=1

a1=3+4×1

a=3+4

=7

let n=2

a2=3+4×2

=3+8

=11

d=a2-a1

d=11-7

d=4

therefore a=7 & d=4.