Question

(a√7-a√6)²+(a√7+a√6)²=?

Answer 1

$...=7a^2-2a^2\sqrt{42}+6a^2+7a^2+2a^2\sqrt{42}+6a^2=26a^2$

Am folosit formulele  $(a\pm b)^2=a^2\pm 2ab+b^2$