Select the correct answer.

What is the simplest form of this expression? [tex]\((x-3)\left(x^2+4x+5\right)\)[/tex]

A. [tex]\(x^3 + 7x^2 + 7x + 15\)[/tex]
B. [tex]\(x^3 + x^2 + 17x + 15\)[/tex]
C. [tex]\(x^3 + x^2 - 7x - 15\)[/tex]
D. [tex]\(x^3 - 7x^2 - 17x - 15\)[/tex]



Answer :

To simplify the expression [tex]\((x - 3)(x^2 + 4x + 5)\)[/tex], follow these steps:

1. Distribute each term in the first binomial to each term in the second trinomial:
[tex]\[ (x - 3)(x^2 + 4x + 5) = x \cdot (x^2 + 4x + 5) - 3 \cdot (x^2 + 4x + 5) \][/tex]

2. Distribute [tex]\( x \)[/tex] across [tex]\( (x^2 + 4x + 5) \)[/tex]:
[tex]\[ x \cdot (x^2 + 4x + 5) = x \cdot x^2 + x \cdot 4x + x \cdot 5 = x^3 + 4x^2 + 5x \][/tex]

3. Distribute [tex]\(-3\)[/tex] across [tex]\( (x^2 + 4x + 5) \)[/tex]:
[tex]\[ -3 \cdot (x^2 + 4x + 5) = -3 \cdot x^2 - 3 \cdot 4x - 3 \cdot 5 = -3x^2 - 12x - 15 \][/tex]

4. Combine the results from both distributions:
[tex]\[ (x - 3)(x^2 + 4x + 5) = x^3 + 4x^2 + 5x - 3x^2 - 12x - 15 \][/tex]

5. Combine like terms:
[tex]\[ x^3 + (4x^2 - 3x^2) + (5x - 12x) - 15 = x^3 + x^2 - 7x - 15 \][/tex]

So, the simplest form of the expression is:
[tex]\[ x^3 + x^2 - 7x - 15 \][/tex]

Therefore, the correct answer is:
[tex]\[ \boxed{\text{C. } x^3 + x^2 - 7x - 15} \][/tex]