Evaluate 3 square root of 7- square root of 63

$3 \sqrt{7} - \sqrt{63}$

Step 1

Simplify each term.

Rewrite $63$ as $3^{2} \cdot 7$ .

Factor $9$ out of $63$ .

$3 \sqrt{7} - \sqrt{9 (7)}$

Rewrite $9$ as $3^{2}$ .

$3 \sqrt{7} - \sqrt{3^{2} \cdot 7}$

Pull terms out from under the radical.

$3 \sqrt{7} - (3 \sqrt{7})$

Multiply $3$ by $- 1$ .

$3 \sqrt{7} - 3 \sqrt{7}$

Step 2

Subtract $3 \sqrt{7}$ from $3 \sqrt{7}$ .

$0$