2x²-2x=5x²-x=5/2(x-1/2)²=5/2+1/4x=(1±√11)/2(x+3)²=(1-2x)²x²+6x+9=1-4x+4x²3x²-10x-8=0(3x+2)(x-4)=03x+2=0x=-2/3或者x-4=0x=4