Question

The term to term rule for a sequence is Multiply by 2 the sequence starts a 2a ___ ___ the total value of the first three terms is 63 work out the total value of the first four terms

Answer 1

135

Explanation:

The sequence are:

a, 2a, 4a, 8a, 16a.....

the total value of the first three terms is 63

That is,

a + 2a + 4a = 63

7a = 63

a = 63/7

a = 9

work out the total value of the first four terms

First four terms are: a, 2a, 4a, 8a

Where,

First term, a = 9

Second term, 2a = 2*9 = 18

Third term, 4a = 4*9 = 36

Fourth term, 8a = 8*9 = 72

The total value of the first four terms = 9 + 18 + 36 + 72

= 135

The total value of the first four terms = 135