Question

$6sqrt{90}$

Explanation:

Step1: Factor 90 into perfect square

$90 = 9 \times 10$

Step2: Simplify the square root

$\sqrt{90} = \sqrt{9 \times 10} = \sqrt{9} \times \sqrt{10} = 3\sqrt{10}$

Step3: Multiply by the coefficient

$6 \times 3\sqrt{10}$

Answer:

$18\sqrt{10}$