Simplify 9 square root of 4-12 square root of 4

$9 \sqrt{4} - 12 \sqrt{4}$

Step 1

Simplify each term.

Rewrite $4$ as $2^{2}$ .

$9 \sqrt{2^{2}} - 12 \sqrt{4}$

Pull terms out from under the radical, assuming positive real numbers.

$9 \cdot 2 - 12 \sqrt{4}$

Multiply $9$ by $2$ .

$18 - 12 \sqrt{4}$

Rewrite $4$ as $2^{2}$ .

$18 - 12 \sqrt{2^{2}}$

Pull terms out from under the radical, assuming positive real numbers.

$18 - 12 \cdot 2$

Multiply $- 12$ by $2$ .

$18 - 24$

Step 2

Subtract $24$ from $18$ .

$- 6$