中二數學三題 要列式 10 ponits!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

把下列公式的主項變做s
1.1/r=ax/x-1+1/s

1/r = ax/x-1 + 1/s
1/r-ax/x-1=1/s
s/r-axs/x-1 = 1
s- axsr/x-1=1
s(x-1)-axsr=1
sx-s-axsr=1
s(x-1-axr)=1
s=1/(x-1-axr)

把下列公式的主項變做x
2.1/r=ax/x-1+1/s
1/r-1/s=ax/x-1
s-r/rs=ax/x-1
s-r(x-1)/rs=ax
s-rx+r/rs=ax
s-rx+r=axrs
s+r=axrs-rx
s+r=xr(as-1)
s+r/[r(as-1)]=x
x=s+r/[r(as-1)]

把下列因式分解
3.a的3次坊-8a的二次坊(只有a是二次坊,8不是二次坊)+16a
a^3-8a^2+16a
=a(a^2-8a+16)
=a(a^2-2(4)(a)+4^2)
=a(a-4)^2

好明顯係功課題，仲要係講到明，幫佢做基本上等於害佢。

1.1/r=ax/(x-1)+1/s
1/r-ax/(x-1)=1/s
s=r-(x-1)/ax
2.1/r=ax/(x-1)+1/s
r=(x-1)/ax+s
3.a^3-8a^2+16a
=a(a^2-8a+16)
=a(a-4)^2

2007-02-26 22:19:22 補充：
2.1/r-1/s=ax/x-1 s-r/rs=ax/x-1 s-r(x-1)/rs=ax s-rx r/rs=ax s-rx r=axrs s r=axrs-rx s r=xr(as-1) s r/[r(as-1)]=x x=s r/[r(as-1)]