Question

Помогите упростить!

1) √2а-2√18а+√72а;

2) √5а-3√20а+√125а.

Answer 1

$1) sqrt{2a}-2 sqrt{18a} + sqrt{72a}=sqrt{2a}-2sqrt{9*2a}+sqrt{36*2a}= \ =sqrt{2a}-2*3sqrt{2a}+6sqrt{2a}=sqrt{2a}-6sqrt{2a}+6sqrt{2a}=sqrt{2a} \ \ 2) sqrt{5a} -3sqrt{20a}+sqrt{125a}=sqrt{5a}-3sqrt{4*5a}+sqrt{25*5a}= \ =sqrt{5a}-3*2sqrt{5a}+5sqrt{5a}=sqrt{5a}-6sqrt{5a}+5sqrt{5a}=0$