How would the expression x2 +8 be rewritten using Sum of Cubes?
A. (x+ 2)(x2 - 2x+4)
B. (x+2)(x2–2x - 4)
C. (x+2)(x2+2x-4)
D. (x-2)(2-2x+4)

Respuesta :

Answer:

[tex]x^3+8=(x+2)(x^2-2x+4)[/tex]

So if they meant [tex]x^3+8[/tex] then the answer is:

[tex](x+2)(x^2-2x+4)[/tex].

The choice this corresponds to is A.

Step-by-step explanation:

The sum of cubes formula for factoring or expanding:

[tex]a^3+b^3=(a+b)(a^2-ab+b^2)[/tex]

You have I'm assuming they meant:

[tex]x^3+8[/tex].

Compare [tex]x^3+8[/tex] to [tex]a^3+b^3[/tex].

You should see in place of [tex]a[/tex] you have [tex]x[/tex].

You should also see in place of [tex]b[/tex] you have [tex]2[/tex].

[tex]a^3+b^3=(a+b)(a^2-ab+b^2)[/tex]

[tex]x^3+8[/tex]

[tex]x^3+2^3[/tex]

[tex]x^3+2^3=(x+2)(x^2-2x+2^2)[/tex]

[tex]x^3+8=(x+2)(x^2-2x+4)[/tex]

Let's check it for fun.

So we are going to use the distributive property.

We are going to distribute all the terms in the first ( ) to all the terms in the second ( ).

[tex]x(x^2-2x+4)[/tex]   +   [tex]2(x^2-2x+4)[/tex]

[tex]x^3-2x^2+4x[/tex]   + [tex]2x^2-4x+8[/tex]

Combine like terms:

[tex]x^3-2x^2+2x^2+4x-4x+8[/tex]

Simplify the grouping of like terms:

[tex]x^3+0x^2+0x+8[/tex]

0 times anything is 0:

[tex]x^3+8[/tex]

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