Question

solve: $5\sqrt{2}\times \sqrt{2}$

Answer 1

$5\times \sqrt{2}\times \sqrt{2}=5\times 2^{\frac{1}{2}}\times 2^{\frac{1}{2}}=5\times 2^{\frac{1}{2}+\frac{1}{2}}$

$=5\times 2^1=10$