2.3.3

Solving Quadratic Inequalities

Test yourself

Quadratic Inequalities

Find inequalities for x when x² > 9 and for x² < 9:

Illustrative background for x&sup2; > 9Illustrative background for x&sup2; > 9 ?? "content

x² > 9

  • Square root both sides.
  • If x² is more than the answer, x must be smaller than the negative or larger than the positive.
Illustrative background for x&sup2; < 9Illustrative background for x&sup2; < 9 ?? "content

x² < 9

  • Square root both sides.
  • If x² is less than the answer, x must be in between the two values.
  • A useful check is to see if x = 0 satisfies the inequality.
    • If it does x must be in between the two square roots.

Jump to other topics

1Proof

2Algebra & Functions

2.1Powers & Roots

2.2Quadratic Equations

2.3Inequalities

2.4Polynomials

2.5Graphs

2.6Functions

2.7Transformation of Graphs

2.8Partial Fractions (A2 Only)

3Coordinate Geometry

4Sequences & Series

5Trigonometry

6Exponentials & Logarithms

7Differentiation

8Integration

9Numerical Methods

10Vectors

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