初3数学,7道计算题! Help Me
问题描述：
初3数学,7道计算题! Help Me
(1)4x^2+12x+9=81
(2)x^2-7x-1=0
(3)2x^2+3x=3
(4)x^2-2x+1=25
(5)x(2x-5)=4x-10
(6)x^2+5x+7=3x+11
答
(1)4x^2+12x+9=814x^2+12x-72=0x^2+3x-18=0(x+6)(x-3)=0x1=-6,x2=3(2)x^2-7x-1=0 x1=(7+根号11)/2,x2=(7-根号11)/2,(3)2x^2+3x=3 2x^2+3x-3=0x1=(-3+根号33)/4,x2==(-3-根号33)/4(4)x^2-2x+1=25 x^2-2x-24=0(x-6)(x+...