What's the 4th term of the sequence defined by An=2a (n-1) + 4; a1=7?

84

Step-by-step explanation:

The sequence is:

An=2a (n-1) + 4

The first term is:

a1=7

So, lets find out A2.

A2 = 2A (2-1) + 4

A2 = 2*A1 + 4

A2 = 2*7 + 4

A2 = 14 + 4 = 18

The third term, A3 is:

A3 = 2A (3-1) + 4

A3 = 2*A2 + 4

A3 = 2*18 + 4 = 36+4 = 40

Finally, the fourth term, A4 is:

A4 = 2A (4-1) + 4

A4 = 2*A3 + 4

A4 = 2*40 + 4 = 80+4 = 84

The 4th term is 84.