Understanding Polynomial Long Division
Polynomial long division is an algorithm for dividing a polynomial by another polynomial of equal or lower degree. It works similarly to long division with numbers: divide the leading term, multiply, subtract, bring down, and repeat until the remainder has a lower degree than the divisor.
The Division Algorithm
Division Theorem
For polynomials f(x) and g(x) with g(x) not zero:
f(x) = g(x) * q(x) + r(x)
Degree Constraint
The remainder always has lower degree than the divisor.
deg(r) < deg(g) or r = 0
Synthetic Division
A shortcut when dividing by (x - c), using only coefficients.
Faster for linear divisors
How to Perform Polynomial Long Division
- Divide: Divide the leading term of the dividend by the leading term of the divisor.
- Multiply: Multiply the entire divisor by the result from step 1.
- Subtract: Subtract the product from the current dividend.
- Bring down: Bring down the next term from the original dividend.
- Repeat: Continue until the degree of the remainder is less than the degree of the divisor.
Applications of Polynomial Division
- Finding roots: If the remainder is zero, the divisor is a factor of the dividend.
- Partial fractions: Decomposing rational expressions for integration in calculus.
- Simplification: Reducing complex rational expressions.
- Factor theorem: Testing whether (x - c) is a factor by checking if f(c) = 0.
- Remainder theorem: The remainder when dividing f(x) by (x - c) equals f(c).
Tips for Success
- Always write polynomials in descending order of degree.
- Include zero coefficients for any missing powers of x.
- Double-check by multiplying the quotient by the divisor and adding the remainder.
- Use synthetic division as a shortcut when the divisor is linear (x - c).