Question

Сократите дробь 3x-9/x^2+4-21. Срочно!

Answer 1

$x^2+4x-21=0\D=16-4cdot(-21)=16+84=100\x_{1,2}=frac{-4pm10}2\x_1=-7,;x_2=3\\frac{3x-9}{x^2+4x-21}=frac{3(x-3)}{(x+7)(x-3)}=frac3{x+7}$