College

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 divide the polynomial [tex]\( x^4 + 5x^3 - 3x - 15 \)[/tex] by [tex]\( x^3 - 3 \)[/tex], we perform polynomial long division. Here are the steps:

1. Setup the division: Write the dividend [tex]\( x^4 + 5x^3 - 3x - 15 \)[/tex] under the long division bar and the divisor [tex]\( x^3 - 3 \)[/tex] on the outside.

2. Divide the leading terms: Divide the leading term of the dividend, [tex]\( x^4 \)[/tex], by the leading term of the divisor, [tex]\( x^3 \)[/tex], which gives [tex]\( x \)[/tex].

3. Multiply and subtract: Multiply [tex]\( x \)[/tex] by the entire divisor [tex]\( x^3 - 3 \)[/tex], which results in [tex]\( x^4 - 3x \)[/tex]. Subtract this product from the original dividend:
[tex]\[
(x^4 + 5x^3 - 3x - 15) - (x^4 - 3x) = 5x^3 + 0x^2 + 0x - 15
\][/tex]

4. Repeat the process: Bring down the next terms if necessary. However, simplify [tex]\( 5x^3 - 15 \)[/tex].

5. Divide the new leading term: Divide the new leading term, [tex]\( 5x^3 \)[/tex], by [tex]\( x^3 \)[/tex], which gives [tex]\( +5 \)[/tex].

6. Multiply and subtract again: Multiply [tex]\( 5 \)[/tex] by [tex]\( x^3 - 3 \)[/tex], resulting in [tex]\( 5x^3 - 15 \)[/tex]. Subtract this from the remaining polynomial:
[tex]\[
(5x^3 - 15) - (5x^3 - 15) = 0
\][/tex]

7. Conclusion: Since the remainder is zero, the division is exact, and the quotient is just the terms we derived from our division: [tex]\( x + 5 \)[/tex].

Thus, the quotient of the division is [tex]\( x + 5 \)[/tex]. This matches option [tex]\( \boxed{x+5} \)[/tex].