Digital SAT · Math · Algebra. The idea in plain words, the rules to remember, the mistake to avoid and a worked example, written and checked by Mega Lecture.
An inequality compares two sides with <, >, ≤ or ≥. Its answer is a range of values, not one number. Solve it like an equation, with one extra rule: when you multiply or divide both sides by a negative number, the sign reverses.
In word problems, translate the phrase with care. At most, no more than and a budget of all mean ≤. At least, no less than and a minimum of all mean ≥. If the answer must be a whole number of items, round in the direction that still satisfies the inequality.
With two variables, a point is a solution only if its coordinates make every inequality in the system true.
Forgetting to reverse the sign after dividing by a negative number. Test one value from your answer in the original inequality to confirm it.
Answer: x = −5
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