5x^2+7x больше или равно 0
5x²+7x≥0 5x(x+1.4)≥0 x(x+1.4)≥0 x=0 x= -1.4 + - + --------- -1.4 ------------ 0 ------------ \\\\\\\\\\\\ \\\\\\\\\\\\\\\ x∈(-∞; -1.4]U[0; +∞)