X(2x+3)-5(x2-3x)=3x(7-x)
X(2x + 3) - 5(x² - 3x) = 3x(7 - x) 2x² + 3x - 5x² + 15x = -3x² + 21x -3x² + 15x + 3x = 21x - 3x² 18x = 21x x = 0 Ответ: x = 0.
2m+m(3-(m+1))=m(2-m)+12
2m+m(3-m-1)= 2m-m²+12
2m+3m-m²-m=2m-m²+12
2m²-2m-12=0
Д= 4 - 4*2*(-12)=4+96=100=10²
x1=2+10/2*2=12/4=3
x2=2-10/2*2=-8/4=-2