Evaluate square root of x+1=4

$\sqrt{x + 1} = 4$

To remove the radical on the left side of the equation, square both sides of the equation.

${\sqrt{x + 1}}^{2} = 4^{2}$

Simplify each side of the equation.

Use $\sqrt[n]{a^{x}} = a^{\frac{x}{n}}$ to rewrite $\sqrt{x + 1}$ as ${(x + 1)}^{\frac{1}{2}}$ .

${({(x + 1)}^{\frac{1}{2}})}^{2} = 4^{2}$

Simplify the left side.

Simplify ${({(x + 1)}^{\frac{1}{2}})}^{2}$ .

Multiply the exponents in ${({(x + 1)}^{\frac{1}{2}})}^{2}$ .

Apply the power rule and multiply exponents, ${(a^{m})}^{n} = a^{m n}$ .

${(x + 1)}^{\frac{1}{2} \cdot 2} = 4^{2}$

Cancel the common factor of $2$ .

Cancel the common factor.

${(x + 1)}^{\frac{1}{2} \cdot 2} = 4^{2}$

Rewrite the expression.

${(x + 1)}^{1} = 4^{2}$

Simplify.

$x + 1 = 4^{2}$

Simplify the right side.

Raise $4$ to the power of $2$ .

$x + 1 = 16$

Move all terms not containing $x$ to the right side of the equation.

Subtract $1$ from both sides of the equation.

$x = 16 - 1$

Subtract $1$ from $16$ .

$x = 15$