Question

The 7th and 13th term of an AP are -4 and -16 respectively. Find a20​

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Answer:

Step-by-step explanation:

a7 =-4 : a+6d=-4    (1)

a13=-16: a+12d=-16   (2)

equation (1) - (2)

a+6d-(a+12d)=-4-(-6)

a+6d-a-12d=-4+6

6d-12d=2

-6d=2

-3=d

a+6d=-4

a+6(-3)=-4

a-18=-4

a=-4+18

a=14

a20=a+(n-1)d

      =14+(20-1)(-3)

      =14+(19)(-3)

      =14-57

a20=-43