(1)4x²+12x+9=81
(2x+3)²=81
2x+3=±9
2x=±9-3
2x=9-3,x1=3
2x=-9-3,x2=-6
(2)x(2x-5)=4x-10
x(2x-5)=2(2x-5)
x(2x-5)-2(2x-5)=0
(x-2)(2x-5)=0
x-2=0,x1=2
2x-5=0,x2=5/2
(3)1-8x+16x²=2-8x
(4x-1)²=-2(4x-1)
(4x-1)²+2(4x-1)=0
(4x-1)(4x-1+2)=0
(4x-1)(4x+1)=0
4x-1=0,x1=1/4
4x+1=0,x2=-1/4
解下列方程:
(2)4x²+12x+9=81
(2x+3)^2=81
2x+3=土9
x1=6 x2=-12
(4)2x²+3x=3
x^2+3x/2=3/2
(x+3/4)^2=3/2+9/16=33/16
x+3/4=土√33/4
x1=(√33-3)/4 x2=-(√33+3)/4 .
(6)x(2x-5)=4x-10
2x^2-5x=4x-10
2x^2-9x+10=0
(x-2)(x-5)=0
x-2=0 x1=2
x-5=0 x2=5
(8) 1-8x+16x²=2-8x
16x^2=1
x^2=1/16
x=土1/4
x1=1/4 x2=-1/4 .
楼上正解