Question

х(2х+3)-5(х²-3х)=3Х(7-Х)

Answer 1

2x^2 + 3x+5x^2  + 15x=21x +3x^2
-6x^2 + 3x+15x=21x
-6x^2   +  18x-21x=0
-3x(2x+1)=0
x=0,   2x=-1
             x=-1/2