Question

The 7th term of an ap is -4 and its 13th term is - 16 find the AP

Answer 1

a7= -4

a+6d= -4-(1)

a13= -16

a+12d= -16-(2)

Subtract (1) from (2)

a+12d= -16

a+6d= -4

(-)(-) (+)

6d= -12

d= -12/6

d= -2

a= -4-6d

a= -4-6(-2)

a= -4+12

a=8

general form of AP is

a,a+d,a+2d........

8,8+(-2),8+2(-2).........

8,8-2,8-4........

8,6,4........