Solving Inequalities
Maths: Edexcel IGCSE Higher, topic 2.6.1
Inequalities
Inequalities are formulae with at least one of <, >, ≤, ≥ in them. Solve the inequality -5x - 2 > 3x:
Write the inequality
Subtract 3x from both sides
Add 2 to both sides
Divide both sides by 8
Multiply both sides by -1
- Note that multiplying or dividing by a negative number switches the direction of the inequality sign.
Double Inequalities
Solve -3 < x⁄2 +3 ≤ 4:
Write the inequality
Multiply both sides and the middle by 2
- This is to get rid of the fraction.
Subtract 6 from both sides and the middle
This is our solution
- We always want x on its own in the middle.
Representing Inequalities
Represent -1 < x ≤ 1 on a number line:
-1 isn't included so draw open circle
1 is included so draw filled in circle
x is in between these values so draw line joining circles
Test yourself on Solving Inequalities
What inequality is represented on this number line?
What inequality is represented on this number line?
What inequality is represented on this number line?
What inequality is represented on this number line?
What inequality is represented on this number line?