Long Division of cubic polynomial

In summary, to solve the expression \frac{x^3+x^2-5x+3}{x^3-3x+2}, you can either use long division by factoring the denominator and using Ruffini's method, or use a shortcut method such as Ruffini's synthetic division.
  • #1
LearninDaMath
295
0

Homework Statement



[itex]\frac{x^3+x^2-5x+3}{x^3-3x+2}[/itex]

Homework Equations





The Attempt at a Solution




well I'm drawing that long division house with x^3-3x+2 on the outside and x^3+x^2-5x+3 on the inside.

I'm seeing that x^3 goes into x^3 one time, so i put a 1 on top of the "house." then I multiply the 1 by x^3-3x+2 and put the product underneath x^3+x^2-5x+3 . However, I can't subtract or add the numbers because the exponents of the x variables don't line. I'm having a problem with the fact that x^3-3x+2 skips the x^2 exponent. I never did a long division problem where the outstide number skipped an exponent. Should I just make a space like x^3+0-3x+2 and let the x^2 from x^3+x^2-5x+3 drop down - kind of like what i would do if the number under the house x^3+x^2-5x+3 skipped a variable?
 
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  • #2
"Should I just make a space like x^3+0-3x+2"
Yes, basically - a better way to visualize it might be
x^3+0x^2-3x+2
 
  • #3
Appreciate it. Much thanks on the clarification.
 
  • #4
LearninDaMath said:

Homework Statement



[itex]\frac{x^3+x^2-5x+3}{x^3-3x+2}[/itex]

Homework Equations





The Attempt at a Solution




well I'm drawing that long division house with x^3-3x+2 on the outside and x^3+x^2-5x+3 on the inside.

I'm seeing that x^3 goes into x^3 one time, so i put a 1 on top of the "house." then I multiply the 1 by x^3-3x+2 and put the product underneath x^3+x^2-5x+3 . However, I can't subtract or add the numbers because the exponents of the x variables don't line. I'm having a problem with the fact that x^3-3x+2 skips the x^2 exponent. I never did a long division problem where the outstide number skipped an exponent. Should I just make a space like x^3+0-3x+2 and let the x^2 from x^3+x^2-5x+3 drop down - kind of like what i would do if the number under the house x^3+x^2-5x+3 skipped a variable?

In this case, the quickest method to do it is as follows: factorise the denominator. There's a linear factor in common between numerator and denominator. Divide the numerator by that factor using a shortcut like Ruffini's synthetic division (should be in the tutorials section, I think, if not, google it). After you do that, divide the resulting quadratic by other factor using Ruffini's method again and get the quotient and remainder.

If you're really required to show the full long division, you have no choice, but if you just need a quick result, the above is a fast and accurate method.
 

What is long division of cubic polynomials?

Long division of cubic polynomials is a method used to divide one cubic polynomial by another cubic polynomial. It is used to simplify complex polynomial expressions and find the quotient and remainder of the division.

How is long division of cubic polynomials performed?

The long division of cubic polynomials is performed by dividing the first term of the dividend (the polynomial being divided) by the first term of the divisor (the polynomial doing the dividing). This results in the first term of the quotient. The resulting term is then multiplied by the entire divisor, and the product is subtracted from the dividend. This process is repeated until the remainder is smaller than the divisor, and the quotient is fully determined.

Why is long division of cubic polynomials important?

Long division of cubic polynomials is important because it allows us to simplify complex polynomial expressions, making them easier to work with. It also helps us find the roots or zeros of a polynomial, which are important in various mathematical applications.

What are the common mistakes made in long division of cubic polynomials?

One common mistake made in long division of cubic polynomials is forgetting to bring down the next term of the dividend after each step. This can result in incorrect terms in the quotient. Another common mistake is incorrectly multiplying the quotient term with the entire divisor, leading to incorrect remainder.

Can long division of cubic polynomials be used for higher degree polynomials?

Yes, long division can be used for polynomials of any degree, not just cubic polynomials. However, as the degree of the polynomial increases, the process can become more complex and time-consuming. Other methods, such as synthetic division, may be more efficient for higher degree polynomials.

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