What is a Dividing Polynomials Calculator?
A Dividing Polynomials Calculator divides one polynomial (the dividend) by another (the divisor) to produce a quotient and a remainder. It supports classical long division for divisors of any degree and synthetic division for linear divisors of the form \(x-a\). By inserting zeros for missing powers and aligning like terms, the calculator systematically cancels the dividend’s leading term at each step, building the quotient term-by-term. The output includes the quotient \(Q(x)\), remainder \(R(x)\), and a verification that \(P(x)=D(x)Q(x)+R(x)\). This is useful for simplifying rational expressions, finding oblique asymptotes, evaluating with the Remainder Theorem, and checking factorization work.
About the Dividing Polynomials Calculator
For polynomials \(P(x)\) and \(D(x)\) with \(\deg P\ge \deg D\) and nonzero leading coefficients, there exist unique \(Q(x)\) and \(R(x)\) such that
\[
P(x)=D(x)\,Q(x)+R(x),\qquad \deg R<\deg D.
\]
Long division cancels the current remainder’s leading term by multiplying the divisor with a suitable monomial and subtracting:
\[
k(x)=\frac{\operatorname{lc}(P)}{\operatorname{lc}(D)}\,x^{\deg P-\deg D},\qquad P\leftarrow P-k(x)D(x).
\]
Synthetic division accelerates division by \(x-a\) using a simple recurrence on coefficients, directly yielding the remainder \(R=P(a)\) (Remainder Theorem). The calculator normalizes sign conventions, supports exact arithmetic for integer/fractional coefficients, and flags undefined operations (e.g., zero divisor).
How to Use this Dividing Polynomials Calculator
- Enter the dividend \(P(x)\) and divisor \(D(x)\) in descending powers (insert zeros for missing terms).
- Select Long Division (any divisor) or Synthetic Division (only when \(D(x)=x-a\)).
- Run the calculation to obtain \(Q(x)\) and \(R(x)\) with step-by-step alignment and cancellations.
- Verify by evaluating \(D(x)Q(x)+R(x)\) and comparing to \(P(x)\).
- (Optional) Factor if \(R(x)=0\), since \(D(x)\) then divides \(P(x)\) exactly.
Core Formulas (LaTeX)
Division algorithm: \[
P(x)=D(x)\,Q(x)+R(x),\quad \deg R<\deg D.
\]
Leading-term step (long division): \[
k(x)=\frac{\mathrm{lc}(P)}{\mathrm{lc}(D)}\,x^{\deg P-\deg D},\quad P\leftarrow P-k(x)D(x).
\]
Synthetic division for \(x-a\): If \(P(x)=\sum_{j=0}^{n} c_j x^{\,n-j}\),
\[
b_0=c_0,\quad b_k=c_k+a\,b_{k-1}\ (k=1,\dots,n),\quad
Q(x)=\sum_{j=0}^{n-1} b_j x^{\,n-1-j},\ R=b_n=P(a).
\]
Remainder Theorem: \[
\text{If } D(x)=x-a,\ \text{then } R=P(a).
\]
Examples (Illustrative)
Example 1 — Synthetic division by \(x-2\)
Divide \(P(x)=2x^3+3x^2-11x+6\) by \(x-2\). Coefficients: \(2,3,-11,6\); use \(a=2\).
Recurrence: \(b_0=2\); \(b_1=3+2\cdot2=7\); \(b_2=-11+2\cdot7=3\); \(b_3=6+2\cdot3=12\).
Quotient \(Q(x)=2x^2+7x+3\), remainder \(R=12\). Check: \((x-2)Q(x)+12=P(x)\).
Example 2 — Long division by a quadratic
Divide \(P(x)=3x^4 - x^3 + 2x - 5\) (note the missing \(x^2\) term) by \(D(x)=x^2-1\).
Steps yield \(Q(x)=3x^2 - x + 3\) and \(R(x)=x-2\). Verify: \(P=DQ+R\).
Example 3 — Remainder Theorem quick check
\(P(x)=x^3-1\) by \(x-1\): remainder \(P(1)=0\Rightarrow\) exact division with \(Q(x)=x^2+x+1\).
FAQs
What’s the difference between long and synthetic division?
Long division works for any divisor; synthetic division is a faster shortcut only for divisors \(x-a\).
Why must I include zero coefficients?
They keep powers aligned so additions and subtractions occur on like terms during division.
How do I know if the division is exact?
If the remainder \(R(x)=0\), then \(D(x)\) divides \(P(x)\) exactly.
Can I divide by a higher-degree polynomial?
Yes—use long division; the quotient will have degree \(\deg P-\deg D\) (or lower), with a remainder of degree less than \(\deg D\).
What does the remainder tell me?
For \(x-a\), the remainder equals \(P(a)\). Nonzero remainders quantify how far from exact divisibility you are.
Does ordering of terms matter?
Yes. Always write polynomials in descending powers; otherwise steps and alignment will be incorrect.