Question

(7а-5b)(7а+5b)-(4a+7b)^2 упростить выражение

Answer 1

49а²-25в²-16а²-56ав-49в²=33а²-74в²-56ав

Answer 2

$(7a-5b)(7a+5b)-(4a+7b)^2= \\ (7a)^2-(5b)^2-[(4a)^2+2*28ab+(7b)^2]= \\ =49a^2-25b^2-16a^2-56ab-49b^2= \\ =(49-16)a^2-56ab-(25+49)b^2= 33a^2-56ab-74b^2$