Which expressions are equivalent to [tex]$x^3-4x$[/tex]? Select all that apply.

A. [tex]$x(x-4)$[/tex]
B. [tex][tex]$x(x+2)^2$[/tex][/tex]
C. [tex]$x\left(x^2-4\right)$[/tex]
D. [tex]$x\left(x^2-4x\right)$[/tex]



Answer :

To determine which expressions are equivalent to [tex]\( x^3 - 4x \)[/tex], we will simplify each given expression and compare it to [tex]\( x^3 - 4x \)[/tex].

Expression A: [tex]\( x(x-4) \)[/tex]
[tex]\[ x(x-4) = x^2 - 4x \][/tex]
This simplifies to [tex]\( x^2 - 4x \)[/tex]. Clearly, [tex]\( x^2 - 4x \)[/tex] is not equivalent to [tex]\( x^3 - 4x \)[/tex].

Expression B: [tex]\( x(x+2)^2 \)[/tex]
[tex]\[ x(x+2)^2 = x(x^2 + 4x + 4) \][/tex]
[tex]\[ = x \cdot x^2 + x \cdot 4x + x \cdot 4 \][/tex]
[tex]\[ = x^3 + 4x^2 + 4x \][/tex]
This simplifies to [tex]\( x^3 + 4x^2 + 4x \)[/tex]. Clearly, [tex]\( x^3 + 4x^2 + 4x \)[/tex] is not equivalent to [tex]\( x^3 - 4x \)[/tex].

Expression C: [tex]\( x(x^2-4) \)[/tex]
[tex]\[ x(x^2-4) = x^3 - 4x \][/tex]
This is already in the required form [tex]\( x^3 - 4x \)[/tex]. Thus, [tex]\( x(x^2-4) \)[/tex] is equivalent to [tex]\( x^3 - 4x \)[/tex].

Expression D: [tex]\( x(x^2-4x) \)[/tex]
[tex]\[ x(x^2-4x) = x^3 - 4x^2 \][/tex]
This simplifies to [tex]\( x^3 - 4x^2 \)[/tex]. Clearly, [tex]\( x^3 - 4x^2 \)[/tex] is not equivalent to [tex]\( x^3 - 4x \)[/tex].

After analyzing each expression, we find that only Expression C: [tex]\( x(x^2-4) \)[/tex] is equivalent to [tex]\( x^3 - 4x \)[/tex].

So, the correct answer is:
- C. [tex]\( x(x^2-4) \)[/tex]