# How do you simplify 7rs(4r^2+9s^3-7rs)?

Oct 31, 2016

$28 {r}^{3} s + 63 r {s}^{4} - 49 {r}^{2} {s}^{2}$

#### Explanation:

Distribute the bracket by multiplying each term in the bracket by 7rs.

$\Rightarrow \textcolor{red}{7 r s} \left(4 {r}^{2} + 9 {s}^{3} - 7 r s\right)$

$= \left(\textcolor{red}{7 r s} \times 4 {r}^{2}\right) + \left(\textcolor{red}{7 r s} \times 9 {s}^{3}\right) + \left(\textcolor{red}{7 r s} \times \left(- 7 r s\right)\right)$

$= 28 {r}^{3} s + 63 r {s}^{4} - 49 {r}^{2} {s}^{2}$