Question

(9-2 \sqrt{7} )(9+2 \sqrt{7})-14*$\sqrt{(-3) ^{2} }$

Answer 1

= 9² - 2²·7 -14·3 = 81 - 28 - 42 = 81 - 70 = 11.

Am folosit :


(a - b)(a + b) = a² - b²