Which of the following is equivalent to [tex]\((x+5)(2x^2+8)\)[/tex]?

A. [tex]\((x+5)(2x)+(x+5)(8)\)[/tex]

B. [tex]\((x+5)(2x^2)+(x+5)(8)\)[/tex]

C. [tex]\((x+5)(2x^2) \cdot (x+5)(8)\)[/tex]

D. [tex]\((x+5)(2x) \cdot (x+5)(8)\)[/tex]



Answer :

To determine which expression is equivalent to [tex]\((x+5)(2x^2 + 8)\)[/tex], we need to expand the given expression using the distributive property.

The distributive property states that [tex]\(a(b + c) = ab + ac\)[/tex]. Applying this property to our expression [tex]\((x+5)(2x^2 + 8)\)[/tex], we have:

[tex]\[ (x+5)(2x^2 + 8) = (x+5) \cdot 2x^2 + (x+5) \cdot 8 \][/tex]

Let's break this down step by step:

1. Distribute [tex]\( (x+5) \)[/tex] to [tex]\( 2x^2 \)[/tex]:
[tex]\[ (x+5) \cdot 2x^2 = 2x^2(x+5) = 2x^2 \cdot x + 2x^2 \cdot 5 = 2x^3 + 10x^2 \][/tex]

2. Distribute [tex]\( (x+5) \)[/tex] to [tex]\( 8 \)[/tex]:
[tex]\[ (x+5) \cdot 8 = 8(x+5) = 8x + 40 \][/tex]

So, combining these results:

[tex]\[ 2x^3 + 10x^2 + 8x + 40 \][/tex]

Now, let's examine the choices given:

A. [tex]\((x+5)(2x) + (x+5)(8)\)[/tex]

Expanding this:
[tex]\[ (x+5) \cdot 2x = 2x(x+5) = 2x^2+10x \][/tex]
[tex]\[ (x+5) \cdot 8 = 8(x+5) = 8x + 40 \][/tex]

Combining these:
[tex]\[ 2x^2 + 10x + 8x + 40 = 2x^2 + 18x + 40 \][/tex]

This is not the same as our expanded expression.

B. [tex]\((x+5)(2x^2) + (x+5)(8)\)[/tex]

Expanding this:
[tex]\[ (x+5) \cdot 2x^2 = 2x^2(x+5) = 2x^3 + 10x^2 \][/tex]
[tex]\[ (x+5) \cdot 8 = 8(x+5) = 8x + 40 \][/tex]

Combining these:
[tex]\[ 2x^3 + 10x^2 + 8x + 40 \][/tex]

This matches our expanded expression.

C. [tex]\((x+5)(2x^2) \cdot (x+5)(8)\)[/tex]

This is not distributive. It means we are multiplying the two resultant quantities, which is not correct.

D. [tex]\((x+5)(2x) \cdot (x+5)(8)\)[/tex]

This is incorrect for the same reason as C; it's a multiplication of two terms rather than distribution.

The correct choice is:

B. [tex]\((x+5)(2x^2) + (x+5)(8)\)[/tex]