解方程48-8X=4(X-2)9(X-8)=11X-8(X-2)

解方程48-8X=4(X-2)9(X-8)=11X-8(X-2)


48-8X=4(X-2)
48-8X=4X-8
8X+4X=48+8
12X=56
X=56÷12
X=14/3
X=3分之14
9(X-8)=11X-8(X-2)
9X-72=11X-8X+16
9X-11X+8X=16+72
6X=88
X=44/3
X=3分之44



設f(x)=x3+4x2+11x+7,則f(-x)為?


f(x)=x^3+4x^2+11x+7
則:
f(-x)=(-x)^3+4(-x)^2+11(-x)+7
=-x^3+4x^2-11x+7
其實就是把-x代替方程中的x.



用拆項法解:X的立方-11X的平方+31X-21


x³;-11x²;+31x-21
=x³;-x²;-(10x²;-31x+21)
=x²;(x-1)-(x-1)(10x-21)
=(x-1)(x²;-10x+21)
=(x-1)(x-3)(x-7)



x²;-4x-12=0解方程求過程


=(x-6)(x+2)
x=6或-2