解方程:3(2x-1)-2(1-x)=0 8x-4=3x+6-12 化简:(2x²-x-1)-(x²-x-1)+(3x²-4)

问题描述:

解方程:3(2x-1)-2(1-x)=0 8x-4=3x+6-12 化简:(2x²-x-1)-
(x²-x-1)+(3x²-4)

3(2x-1)-2(1-x)=0
6x-3-2+2x=0
4x-5=0 因此x=5/4
8x-4=3x+6-12
解5x=-2 x=-2/5

(2x²-x-1)- (x²-x-1)+(3x²-4)= 4x²-4

换元法,先化简

3(2x-1)-2(1-x)=0
6x-3-2+2x=0
8x=5
x=5/8
8x-4=3x+6-12
5x= -2
x= -2/5
化简:
(2x²-x-1)-(x²-x-1)+(3x²-4)
=2x²-x-1-x²+x+1+3x²-4
=4x²-4
=4(x+1)(x-1)