# How do you solve 5sqrt(x+1)=21?

May 12, 2018

$x = \frac{416}{25}$

#### Explanation:

Solve:

$5 \sqrt{x + 1} = 21$

Square both sides.

$25 \left(x + 1\right) = 441$

Divide both sides by $25$

$x + 1 = \frac{441}{25}$

Subtract $1$ from both sides.

$x = \frac{441}{25} - 1$

Multiply $1$ by $\frac{25}{25}$ to get an equivalent fraction with $25$ as the denominator.

$x = \frac{441}{25} - 1 \times \frac{25}{25}$

$x = \frac{441}{25} - \frac{25}{25}$

Simplify.

$x = \frac{416}{25}$

May 12, 2018

#### Explanation:

5 √(x+1) =21

Divide:

(5√x+1)/5 = 21/5 or 4.2

Square (the opposite of square root):

(√(x+1))^2= 4.2^2 or 17.64

Subtract:

$x + 1 - 1 = 17.64 - 1$

$x = 16.64$