Question

(2+√5)² - ( 2 -√5)² 
CẦN GẤP!!!!!!!!!!!!!!

Answer 1

\(=4+2.2.\sqrt{5}+5-\left(4-2.2.\sqrt{5}+5\right)\\ =9+4\sqrt{5}-9+4\sqrt{5}\\ =8\sqrt{5}\)

Answer 2

=4+2.2.√5+5−(4−2.2.√5+5)

=(4+5)+4√5-(4+5)-4√5

=9+4√5−9+4√5

=8√5

Answer 3

=\(4+4+2\sqrt{5}+5-4+4+2\sqrt{5}-5\)

=\(8+4\sqrt{5}\)