(32-2x)x=120 32x-2x^2=120x^2-16x+60=0(x-10)(x-6)=0x-10=0 x-6=0x1=10 或 x2=6(x+3)^2=-x(x+5) x^2+6x+9=-x^2-5x2x^2+11x+9=0(2x+9)(x+1)=02x+9=0x+1=0x1=-9/2或者x2=-1