Linear Inequalities
Solve like an equation — but watch the flip.
Concept
One extra rule
Every move you use on equations works on inequalities, with a single exception: multiplying or dividing both sides by a negative number reverses the inequality sign.
Sanity check it with numbers: 2 < 4 is true, but multiplying by −1 gives −2 > −4, not −2 < −4.
if a < b and k < 0 then ka > kb