Revision sheet

Linear equations

Do the same to both sides until $x$ is alone.

Watch out: distribute to every term.

Solving for a variable

Same moves as with numbers; the other letters are just numbers you do not know.

Watch out: divide every term.

Inequalities

Solve as an equation; flip when multiplying or dividing by a negative.

Watch out: check with a number from your answer.

Absolute value equations and inequalities

|x − a| = b: a ± b. Less than: between. Greater than: outside.

Watch out: do not forget the negative case.

Lines from equations

Intercepts: set the other variable to 0. Slope: solve for $y$.

Watch out: slope of $Ax + By = C$ is $-A/B$.