Question

(√m + √5)² - (m+5) пж​

Answer 1

По формуле квадрата суммы:

$(x + y) {}^{2} = {x}^{2} + 2xy + {y}^{2} \\ ( \sqrt{m} + \sqrt{5} ) {}^{2} = ( \sqrt{m} ) {}^{2} + 2 \sqrt{m} \sqrt{5} + ( \sqrt{5} ) {}^{2} = \\ = m + 2 \sqrt{5m} + 5$

$( \sqrt{m} + \sqrt{5} ) {}^{2} -( m + 5) = \\ = m + 2 \sqrt{5m} + 5 - m - 5 = 2 \sqrt{5m}$