High School

The quotient of [tex]\left(x^4+5x^3-3x-15\right)[/tex] and [tex]\left(x^3-3\right)[/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 division of two polynomials, [tex]\((x^4 + 5x^3 - 3x - 15)\)[/tex] divided by [tex]\((x^3 - 3)\)[/tex], we perform polynomial long division.

Here is the step-by-step process:

1. Divide the first term of the dividend by the first term of the divisor:

The first term of the dividend is [tex]\(x^4\)[/tex], and the first term of the divisor is [tex]\(x^3\)[/tex]. Dividing these gives:
[tex]\[
\frac{x^4}{x^3} = x
\][/tex]

2. Multiply the entire divisor by this result:

Multiply [tex]\(x\)[/tex] by [tex]\((x^3 - 3)\)[/tex]:
[tex]\[
x \cdot (x^3 - 3) = x^4 - 3x
\][/tex]

3. Subtract this from the original dividend:

Subtract [tex]\((x^4 - 3x)\)[/tex] from [tex]\((x^4 + 5x^3 - 3x - 15)\)[/tex]:
[tex]\[
(x^4 + 5x^3 - 3x - 15) - (x^4 - 3x) = 5x^3 + 0x - 15
\][/tex]

4. Bring down the next term:

After subtraction, the current expression is [tex]\(5x^3 - 15\)[/tex].

5. Repeat the division process with the new polynomial:

Divide the first term ([tex]\(5x^3\)[/tex]) by the first term of the divisor ([tex]\(x^3\)[/tex]):
[tex]\[
\frac{5x^3}{x^3} = 5
\][/tex]

6. Multiply the entire divisor by this new result:

Multiply [tex]\(5\)[/tex] by [tex]\((x^3 - 3)\)[/tex]:
[tex]\[
5 \cdot (x^3 - 3) = 5x^3 - 15
\][/tex]

7. Subtract this from the current polynomial:

Subtract [tex]\((5x^3 - 15)\)[/tex] from [tex]\(5x^3 - 15\)[/tex]:
[tex]\[
(5x^3 - 15) - (5x^3 - 15) = 0
\][/tex]

At this point, the remainder is zero, which confirms that our division process is complete, and the quotient is a polynomial [tex]\(x + 5\)[/tex].

Therefore, the quotient of [tex]\((x^4 + 5x^3 - 3x - 15)\)[/tex] divided by [tex]\((x^3 - 3)\)[/tex] is [tex]\(x + 5\)[/tex].