Question

For the A.P. -3,-7,-11... can we find directly a30 - a20 without actually finding a30 and a20? Give reasons for your answer.

Answer 1

hope tis helps you

Step-by-step explanation:

find the common difference

d= -7-(-3)

= -7+3

d=-4

a20= a+19d

-3+19×-4

-3-76

-79

A30= a+29d

-3+29×-4

-3-116

-119

a30-a20= -119 - (-79)

-119+79

= -40