(58+27) · 3 = 255
1) 58+27=85
2) 85 · 3 = 255
Ответ:255
x³+7x² = 4x+28
x²(x+7) = 4(x+7)
x²(x+7)-4(x+7) = 0
(x+7)(x²-4) = 0
(x+7)(x-2)(x+2) = 0
x = -7
x = ±2
5x-2y=39