What is 6 square root 45 plus 2 square root 80?

Mar 2, 2018

$26 \sqrt{5}$.

Explanation:

$6 \sqrt{45} + 2 \sqrt{80}$,

$= 6 \sqrt{{3}^{2} \times 5} + 2 \sqrt{{4}^{2} \times 5}$,

$= 6 \times \sqrt{{3}^{2}} \times \sqrt{5} + 2 \times \sqrt{{4}^{2}} \times 5$,

$= 6 \times 3 \times \sqrt{5} + 2 \times 4 \times \sqrt{5}$,

$= 18 \sqrt{5} + 8 \sqrt{5}$,

$= 26 \sqrt{5}$.