MATH Question about function(easy)

👨🏻‍🏫 學術台數學

[匿名]

2008-10-05 12:55 am

f(x)=(x+1)^2,then f(x-1)=?

f(x)=x^2,thenf(x+y)-f(x-y)=?

回答 (2)

死亡天才 Death Genius

2008-10-05 1:14 am

✔ 最佳答案

1) f(x)=(x+1)2
f(x-1)=(x-1+1)2=x2

2) f(x)=x2
f(x+y)-f(x-y)= (x+y)2-(x-y)2= x2+2xy+y2-x2+2xy-y2= 4xy

參考: me

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Descartes

2008-10-05 5:36 am

Since f(x)=(x+1)^2
f(x+1) = [(x-1)+1]^2
=x^2

Since f(x)=x^2
f(x+y) - f(x-y)
=(x+y)^2 - (x-y)^2
=(2x)(2y) [ A^2-B^2 = (A+B)(A-B) ]
=4xy

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