5x+4 + 2*
+ 2x - 1 =3x+1
2*
= 6-4x
4 (5x-4)(2x-1) = 36 - 48x + 16x²
40x² - 20x - 32x + 16 - 36 + 48x - 16x² = 0
24x² - 4x - 20 = 0
6x² - x - 5 =0
6 - 1 -5=0
x₁ = 1
x₂ = -5/6 не удов., т.к. 5x-1≥0
Ответ: 1
=t^2-7t+3t-21-t^2=-4t-21=-4*(-14)-21=56-21=35