1.﹛x-2-[12/(x+2)]﹜÷(4-x)/(x+2) 2.解方程3/(x-1)-(x+3)/(x²-1)=0
1个回答

(1)

﹛x-2-[12/(x+2)]﹜÷(4-x)/(x+2)

=[x-2-12/(x+2)]÷[(4-x)/(x+2)]

={ [(x-2)(x+2)-12]/(x+2) }×[(x+2)/(4-x)]

=[(x²-4-12)/(x+2)]×[-(x+2)/(x-4)]

=(x²-16)×[-1/(x-4)]

=(x+4)(x-4)×[-1/(x-4)]

=-(x+4)

=-x-4

(2)

3/(x-1)-(x+3)/(x^2-1)=0

3(x+1)/(x-1)(x+1)-(x+3)/(x-1)(x+1)=0

[3(x+1)-(x+3)]/(x-1)(x+1)=0

(3x+3-x-3)/(x-1)(x+1)=0

2x/(x-1)(x+1)=0

2x=0

x=0

经检验x=0是方程的解