High School

The quotient of [tex]x^4 + 5x^3 - 3x - 15[/tex] and [tex]x^3 - 3[/tex] is a polynomial. What is the quotient?

A. [tex]x^7 + 5x^6 - 6x^4 - 30x^3 + 9x + 45[/tex]
B. [tex]x - 5[/tex]
C. [tex]x + 5[/tex]
D. [tex]x^7 + 5x^6 + 6x^4 + 30x^3 + 9x + 45[/tex]

Answer :

To find the quotient of the polynomials [tex]\((x^4 + 5x^3 - 3x - 15)\)[/tex] and [tex]\((x^3 - 3)\)[/tex], we will perform polynomial long division.

### Step-by-step solution:

1. Set up the division: Write the dividend, which is the numerator [tex]\(x^4 + 5x^3 - 3x - 15\)[/tex], and the divisor, which is the denominator [tex]\(x^3 - 3\)[/tex].

2. Divide the first term: Look at the first term of the dividend [tex]\(x^4\)[/tex] and the first term of the divisor [tex]\(x^3\)[/tex]. Divide these to get the first term of the quotient: [tex]\(\frac{x^4}{x^3} = x\)[/tex].

3. Multiply and subtract: Multiply the entire divisor [tex]\(x^3 - 3\)[/tex] by this first term of the quotient [tex]\(x\)[/tex]. Then, subtract this result from the original polynomial:
- Multiply: [tex]\(x(x^3 - 3) = x^4 - 3x\)[/tex]
- Subtraction: [tex]\((x^4 + 5x^3 - 3x - 15) - (x^4 - 3x)\)[/tex] results in [tex]\(5x^3 + 0x^2 - 3x - 15\)[/tex].

4. Repeat the division process: Now treat [tex]\(5x^3 + 0x^2 - 3x - 15\)[/tex] as the new dividend.
- Divide [tex]\(5x^3\)[/tex] by [tex]\(x^3\)[/tex] to get [tex]\(5\)[/tex].
- Multiply and subtract:
- Multiply: [tex]\(5(x^3 - 3) = 5x^3 - 15\)[/tex]
- Subtract: [tex]\((5x^3 - 3x - 15) - (5x^3 - 15)\)[/tex] results in [tex]\(0x^2 - 3x + 0\)[/tex].

5. Determine the end of division: Since the degree of the new expression [tex]\( -3x\)[/tex] is less than the degree of the divisor [tex]\(x^3 - 3\)[/tex], we stop here.

After performing these steps, the quotient of [tex]\((x^4 + 5x^3 - 3x - 15)\)[/tex] divided by [tex]\((x^3 - 3)\)[/tex] is:

[tex]\[ x + 5 \][/tex]

So, the correct answer is [tex]\(x + 5\)[/tex].