1. 原败腊方咐数程可化为x²-6x-2=0,由根式判别法可得Δ=b²-4ac=36+8=44,于是有根
x1=3+√11, x2=3-√11
2. 原方程可化为2(x²察简滑+1.5x-2)=0
==>2(x²+1.5x+9/16)-41/8=0
==>(x+3/4)²=41/16
==>x=±√41/4-3/4
3. 原方程可化为x²-4x-3=0
==>Δ=16+12=28
==>x1=2+√7, x2=2-√7
解:
(1)(配高乱方法)旅碰
(1/2)x2-3x=1
→x2-6x-2=0
→x2-6x+9-9-2=0
(x-3)2=11
∴x1= 3+√11 x2= 3-√11
(2)(配方法)
2x2+3x-4=0
→x2+(3/2)x-2=0
x2+2×(3/4)x+(3/4)2-(3/4)2 -2=0
(x+3/拆念谈4)2=2+(9/16)=41/16
x+3/4=±√41/4
∴x1= √41-3/4 x2= -(3+√41/4)
(3)x(x-3)-x=3(配方法)
x2-3x-x-3=0
x2-4x-3=0
x2-4x+4-3-4=0
(x-2)2=7
x-2=±√7
∴x1= 2+√7 x2=2-√7