Credible sums

Algebra Level 4

If $(1.5)^{30}=k$ , then state $\displaystyle\sum_{n=2}^{29}(1.5)^{n}$ in terms of $k$ .

none of these

2k-3

2k+1

2k-\frac{9}{2}

2k+7

\infty

1 solution

Ravi Dwivedi
Jul 4, 2015

The required expression is a G.P. with first term= (1.5)^2 and common ratio=1.5

Let the expression to be calculated be E.

Simple standard approach