Question

How do i solve this guyz? o.O

Answer 1

http://screencast.com/t/zh7s2oXxBL

Answer 2

I need to solve this two equations.

\[a r^{2} = 20----->1\]
\[\frac{a}{1-r} = 3a\]

Answer 3

@.Sam. @robtobey

Answer 4

they're saying that \[T_3=20 \\ \\ S_\infty=3T_1\]

Answer 5

\[T_3=20 ...(1) \\ \\ S_\infty=3T_1 ...(2)\]
\[(1)\\ \\ a_1r^{n-1}=30 \\ \\ a_1r^2=30 \\ \\ \text{We know that T_1=a_1} \\ \\ (2) \\ \\ \frac{a_1}{1-r}=3a_1 \\ \\ r=\frac{2}{3} \]
Substitute r into (1) and you have a1

Answer 6

thnks alot

Answer 7

yw