Question

Solve the equation by Factoring

Answer 1

First set the equation to zero by adding -400 to both sides.

`16 {r}^(2) - 400 = 0`
Next factor 16

`16 ({r}^(2) - 25)= 0`

Divide through by 16

`\frac{16 ({r}^(2) - 25)}{16} = (0)/(16)`

`({r}^(2) - 25)= 0`

This is difference of two squares


`(r - 5)(r + 5) = 0`

`either \: r - 5= 0 \: or \: r + 5= 0`

`r = 5 \: or \: - 5`