F.4 MATHS!

1.x/2 = 4 - 8/x
(x/2)2x =(4 - 8/x)2x
x^2=8x-16
x^2-8x+16=0
(x-4)^2=0
x=4

2.x+3/x-1 = 5
(x+3/x-1)x=5x
x^2-x+3=5x
x^2-6x+3=0
x^2-6x+9-6=0
(x-3)^2=6
x=√6+3or3-√6

3.√2x+3=x
2x+3=x^2
x^2-2x-3=0
(x-1)(x+3)=0
x=1or-3

4.2√x-3=x-6
4x-12=x^2-12x+36
x^2-16x+48=0
(x-4)(x-12)=0
x=4or12

5.x=5-√x+1
x-5=-√x+1
x^2-10x+25=x+1
x^2-11x+24=0
x^2-11x+121-97=0
(x-11)^2=97
x=√97+11or11-√97

2006-11-26 21:39:16 補充：
12/x+1 = x - 312+x=x^2-3xx^2-4x-12=0(x-6)(x+2)=0x=6or-2