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 [tex]\( \left(x^4 + 5x^3 - 3x - 15\right) \)[/tex] divided by [tex]\( \left(x^3 - 3\right) \)[/tex], we need to perform polynomial long division. Let's go through the steps:

1. Divide the first term of the dividend [tex]\( x^4 \)[/tex] by the first term of the divisor [tex]\( x^3 \)[/tex]:
[tex]\[
\frac{x^4}{x^3} = x
\][/tex]
So, the first term of the quotient is [tex]\( x \)[/tex].

2. Multiply [tex]\( x \)[/tex] by the entire divisor [tex]\( x^3 - 3 \)[/tex] to get:
[tex]\[
x \cdot (x^3 - 3) = x^4 - 3x
\][/tex]

3. Subtract the result from the original polynomial:
[tex]\[
(x^4 + 5x^3 - 3x - 15) - (x^4 - 3x) = 5x^3 + 0 - 15
\][/tex]
Simplifying gives:
[tex]\[
5x^3 - 15
\][/tex]

4. Divide the new leading term [tex]\( 5x^3 \)[/tex] by [tex]\( x^3 \)[/tex]:
[tex]\[
\frac{5x^3}{x^3} = 5
\][/tex]
Add [tex]\( 5 \)[/tex] to the quotient.

5. Multiply [tex]\( 5 \)[/tex] by the divisor [tex]\( x^3 - 3 \)[/tex] to get:
[tex]\[
5 \cdot (x^3 - 3) = 5x^3 - 15
\][/tex]

6. Subtract this from the current dividend:
[tex]\[
(5x^3 - 15) - (5x^3 - 15) = 0
\][/tex]

Since we are left with 0 as the remainder, the division is complete. The quotient is:

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

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