Question

Simplify the expression: 2√ 20 − 3√ 7 − 2√ 5 + 4√ 63 . A. 2√ 20 − 3√ 7 − 2√ 5 + 4√ 63 B. 2√ 5 + 9√ 7 C. 2√ 20 − 4√ 7 − 2√ 5 D. 2√ 20 − 3√ 7 + 4√ 63

Answer 1

$2 \sqrt{20}- 3\sqrt{7}-2 \sqrt{5}+4 \sqrt{63}=2 \sqrt{4*5}- 3\sqrt{7}-2 \sqrt{5}+4 \sqrt{9*7}= \\ \\ 2 *2\sqrt{5}- 3\sqrt{7}-2 \sqrt{5}+4*3 \sqrt{7}=4\sqrt{5}- 3\sqrt{7}-2 \sqrt{5}+12 \sqrt{7}= \\ \\ =2 \sqrt{5}+9 \sqrt{7}$

Answer: B. 2√5 + 9√7 

Answer 2

B is the right option. hope it helps