IGCSE Revision Lesson 9

I can represent inequalities graphicallyI can solve simple linear inequalities

≤≥

> <

IGCSE Revision Lesson 9

Graphically represent:x > 5 x < 4 x ≤ 2 x ≥ -3x is more than 5 x is less than 4 x is smaller than x is greater than

or equal to 2 or equal to -3

5 4 2 -3

hollow circle indicates that the number is not included

filled circle indicates that the number is included

IGCSE Revision Lesson 9

If you double my age, the answer is more than 50. How old am I?

If x is my age, form and solve an inequality.

Give three integer values that satisfy your inequality.

IGCSE Revision Lesson 9

If you triple my age and add 5, the answer is less than 126.

Form and solve an inequality.

What is the maximum age I could have been at my last birthday?

IGCSE Revision Lesson 9

-3x < -6

If you multiply by a negative number, the sign changes round. The best thing is to avoid multiplying by a negative.

Two types of question:

“Solve the inequality” means “give the complete range”

“Write down an integer value” means “give a certain example” (e.g. the largest, smallest...)