Question

Найдите значение выражений

Answer 1

(a² - b²)/(2a - 2b) - a =
= (a - b)(a + b)/2(a - b) - a=
(a + b)/2 - a = 
= (5+7)/2 - 5 = 12/2 - 5 = 1
OTVET: 1

Answer 2

$\frac{a^2-b^2}{2a-2b} -a = \frac{(a-b)(a+b)}{2(a-b)} - a = \frac{a+b}{2} -a = \\ \\ = \frac{a+b - 2*a}{2} = \frac{b -a}{2} = \frac{1}{2} (b-a) = 0.5(b-a) \\ \\ a= 5 , b=7 \\ 0.5*(7-5) = 0.5*2 = 1$