# How to work out /17^2-15^2?

Dec 28, 2017

64

#### Explanation:

The difference of two squares can be written as

${a}^{2} - {b}^{2} = \left(a + b\right) \left(a - b\right)$

Using this formula,

${17}^{2} - {15}^{2} = \left(17 + 15\right) \left(17 - 15\right)$
${17}^{2} - {15}^{2} = \left(32\right) \left(2\right)$
${17}^{2} - {15}^{2} = 64$

Dec 28, 2017

$64$

#### Explanation:

$\text{using the "color(blue)"difference of squares}$

•color(white)(x)a^2-b^2=(a-b)(a+b)

$\Rightarrow {17}^{2} - {15}^{2}$

$= \left(17 - 15\right) \left(17 + 15\right)$

$= 2 \times 32 = 64$