定義Mf(x)=f(x+1)-f(x)為函數(shù)f(x)的邊際函數(shù)，某利潤P（x）=-x3+30x2+1010(x∈［10,25］且x∈N),則他的邊際函數(shù)是？

熱心網(wǎng)友

P(x+1) = -(x+1)^3+30(x+1)^2 + 1010 (x+1∈［10,25］且x+1∈N)P(x+1)-P(x)= [ -(x+1)^3+30(x+1)^2 + 1010 ] - [-x^3+30x^2 + 1010]=x^3-(x+1)^3 + 30(x+1)^2 - 30x^2= -3x^2 -3x -1 + 60x +30= -3x^2 +57x +29此即為邊際函數(shù)。x的定義域為 x∈［10,24］且x∈N