巧算:(1+1:2+1:3+1:4)*(1:2+1:3+1:4+1:5)-(1+1:2+1:3+1:4+1:5)*(1:2+1:3+1:4)

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巧算:(1+1:2+1:3+1:4)*(1:2+1:3+1:4+1:5)-(1+1:2+1:3+1:4+1:5)*(1:2+1:3+1:4)

巧算:(1+1:2+1:3+1:4)*(1:2+1:3+1:4+1:5)-(1+1:2+1:3+1:4+1:5)*(1:2+1:3+1:4)
巧算:(1+1:2+1:3+1:4)*(1:2+1:3+1:4+1:5)-(1+1:2+1:3+1:4+1:5)*(1:2+1:3+1:4)

巧算:(1+1:2+1:3+1:4)*(1:2+1:3+1:4+1:5)-(1+1:2+1:3+1:4+1:5)*(1:2+1:3+1:4)
令a=1:2+1:3+1:4
则1+1:2+1:3+1:4=1+a
1:2+1:3+1:4+1:5=a+1:5
1+1:2+1:3+1:4+1:5=1+a+1:5
所以原式=(1+a)(a+1:5)-a(1+a+1:5)
=a(1+a)+(1+a)×1:5-a(1+a)-a×1:5
=1×1:5+a×1:5-a×1:5
=1:5

对数：n=log(a)(b) .(其中a>0且a≠1，b>0)
设此对数为：y=f(x)=log(a)(x) (a为下标)
由题意知过点M(9,2)
因此有：2= log(a)(9)
得：a=3
因此函数表达式为：y=f(x)=log(3)(x)
因此：f(1)=log(3)(1)=0, f(3)=log(3)(3)=1

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