X^2+2x-3 --------------------- больше или равно 0 (x-7)(x+5)
X²+2x-3=0 x1+x2=-2 U x1*x2=-3⇒x1=-3 U x2=1 x-7=0⇒x=7 x+5=0⇒x=-5 + _ + _ + ----------(-5)------------[-3]----------[1]---------------(7)-------------- x∈(-∞;-5) U [-3;1] U (7;∞)