College

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 :

We start by dividing the polynomial

[tex]$$
x^4 + 5x^3 - 3x - 15
$$[/tex]

by

[tex]$$
x^3 - 3.
$$[/tex]

Step 1: Divide the leading terms

The highest degree term in the dividend is [tex]$x^4$[/tex], and in the divisor it is [tex]$x^3$[/tex]. Dividing these gives:

[tex]$$
\frac{x^4}{x^3} = x.
$$[/tex]

So, the first term of the quotient is [tex]$x$[/tex].

Step 2: Multiply and subtract

Multiply the entire divisor by [tex]$x$[/tex]:

[tex]$$
x(x^3 - 3) = x^4 - 3x.
$$[/tex]

Subtract this product from the dividend:

[tex]\[
\begin{array}{rcl}
x^4 + 5x^3 - 3x - 15 & - & (x^4 - 3x) \\
\hline
& = & 5x^3 - 15.
\end{array}
\][/tex]

Step 3: Repeat the process

Now, we take the new dividend [tex]$5x^3 - 15$[/tex]. Divide the leading term [tex]$5x^3$[/tex] by the leading term of the divisor [tex]$x^3$[/tex]:

[tex]$$
\frac{5x^3}{x^3} = 5.
$$[/tex]

This gives the next term of the quotient, which is [tex]$5$[/tex].

Multiply the divisor by [tex]$5$[/tex]:

[tex]$$
5(x^3 - 3) = 5x^3 - 15.
$$[/tex]

Subtract this from the current dividend:

[tex]\[
(5x^3 - 15) - (5x^3 - 15) = 0.
\][/tex]

The remainder is [tex]$0$[/tex], which means the division is exact.

Step 4: Write the quotient

The quotient obtained is the sum of the terms calculated:

[tex]$$
x + 5.
$$[/tex]

Thus, the quotient of the division of [tex]$x^4+5x^3-3x-15$[/tex] by [tex]$x^3-3$[/tex] is

[tex]$$
\boxed{x + 5}.
$$[/tex]