# How do you simplify (9xy^7)^2?

Feb 19, 2017

${\left(9 x {y}^{7}\right)}^{2} = 81 {x}^{2} {y}^{14}$

#### Explanation:

Squaring a number or expression means multiplying it by itself.

${\left(9 x {y}^{7}\right)}^{2} = \left(9 x {y}^{7}\right) \times \left(9 x {y}^{7}\right)$

$= 81 {x}^{2} {y}^{14}$

In the same way ${\left(9 x {y}^{7}\right)}^{3} = \left(9 x {y}^{7}\right) \times \left(9 x {y}^{7}\right) \times \left(9 x {y}^{7}\right)$

A common error is to multiply by 2.

$\left(9 x {y}^{7}\right) \times 2 = 18 x {y}^{7}$ which gives a completely different result.