Question

Find the 12th term of the arithmetic sequence -3x+8, 4x+5, 11x+2, ....

Please help me

Answer 1

74x - 25.

Explanation:

The common difference d

= 4x + 5 - (-3x + 8)

= 7x - 3

also:

11x + 2 - (4x + 5)

= 7x - 3.

First term a1 = -3x + 8

so, 12th term

= a1 + (n -1)d

= -3x + 8 + (12 - 1)(7x - 3)

= -3x + 8 + 11(7x - 3)

= -3x + 8 + 77x - 33

= 74x - 25.