解方程x2-3ax+(2a2-a-1)=0
问题描述：
解方程
x2-3ax+(2a2-a-1)=0
答
用因式分解法方便，也可用公式法.
答
x^2-3ax+(2a2-a-1)=0
x^2-3ax+9a^2/4-9a^2/4+(2a2-a-1)=0
(x-3a/2)^2-a^2/4-a-1=0
(x-3a/2)^2-(a^2+4a+4)/4=0
(x-3a/2)^2-(a+2)^2/4=0
[(x-3a/2)-(a+2)/2][(x-3a/2)+(a+2)/2]=0
(x-2a-1)(x-a+1)=0
x=2a+1 或 x=a-1
答
化简:
X2+2*3/2ax+9/4a2-1/4a2-a-1=0
(X-3/2a)2-(1/2a+1)2=0
(X-3/2a+1/2a+1)(X-3/2a-1/2a-1)=0
(X-a+1)(X-2a-1)=0
所以得出X=a-1或X=2a+1
答
x2-3ax+(2a2-a-1)=0
x^2-3ax+(2a+1)(a-1)=0
[x-(2a+1)][x-(a-1)]=0
x1=2a+1
x2=a-1
答
2a²-a-1=(2a+1)(a-1)-3a=[-(2a+1)]+[-(a-1)]所以x²+[-(2a+1)]x+[-(a-1)]x+(2a+1)(a-1)=0x[x-(2a+1)]-(a-1)[x-(2a+1)]=0[x-(2a+1)][x-(a-1)]=0x=2a+1,x=a-1