2.8.5

Partial Fractions - Practice

Test yourself on Partial Fractions - Practice

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What are Partial Fractions?

If an algebraic fraction has a numerator that is lower in degree than its denominator, we can split it up into partial fractions. This allows us to do calculations more easily.

What are the linear factors in a denominator?

What are the linear factors in a denominator?

  • To split up an algebraic fraction into its partial fractions, we need to factorise the denominator into its linear factors.
    • For example, 11x72x33x22x11x7x(2x+1)(x2)\frac{\small 11x-7}{\small 2x^3 -3x^2 -2x} \rightarrow \frac{\small 11x-7}{\small x(2x + 1)(x-2)}
Fractions with 2 linear factors

Fractions with 2 linear factors

  • If a fraction has a denominator consisting of 2 different linear factors, we can express it as the sum of partial fractions:
    • For example, 11x7(2x+1)(x2)A2x+1+Bx2\frac{\small 11x-7}{\small (2x + 1)(x-2)} \equiv \frac{\small A}{\small 2x+1} + \frac{\small B}{\small x-2}
  • Where AA and BB are constants.
  • These constants are found by adding the fractions and either substituting in values of xx or by equating coefficients of xx.
Fractions with 3 linear factors

Fractions with 3 linear factors

  • If a fraction has a denominator consisting of 3 different linear factors, we can express it as the sum of partial fractions.
    • For example, 2x+4(x+3)(3x+1)(x2)Ax+3+B3x+1+Cx2\frac{\small 2x+4}{\small (x + 3)(3x+1)(x-2)} \equiv \frac{\small A}{\small x+3} + \frac{ \small B}{\small 3x+1}+\frac{\small C}{\small x-2}
  • Where AA, BB and CC are constants to be found by substitution or equating coefficients.
Fractions with repeated factors

Fractions with repeated factors

  • If a fraction has a denominator consisting of 2 different linear factors and one is repeated, we can express it as the sum of partial fractions:
    • For example, 5(x1)(3x+2)2Ax1+B3x+2+C(3x+2)2\frac{5}{(x-1)(3x+2)^2} \equiv \frac{A}{x-1} + \frac{B}{3x+2} + \frac{C}{(3x+2)^2}
  • Where AA, BB and CC are constants to be found by substitution or equating coefficients.
Jump to other topics
1

Proof

2

Algebra & Functions

2.1

Powers & Roots

2.2

Quadratic Equations

2.3

Inequalities

2.4

Polynomials

2.5

Graphs

2.6

Functions

2.7

Transformation of Graphs

2.8

Partial Fractions (A2 Only)

3

Coordinate Geometry

4

Sequences & Series

5

Trigonometry

6

Exponentials & Logarithms

7

Differentiation

8

Integration

9

Numerical Methods

10

Vectors

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