Menu

Brackets and a Flip

Part of the Inequalities & Absolute Value section of Coddy's Algebra journey. Lesson 57 of 61.

A longer inequality is solved with the same steps as a short one, done one after another. Take 3(x−2)≥5x−43\left(x-2\right) \ge 5x-4. Open the bracket, collect the xx terms on the left and the numbers on the right, then divide. The coefficient left in front of xx is negative, so the last division flips the sign.

3x−6≥5x−43x-6 \ge 5x-4

−2x−6≥−4-2x-6 \ge -4

−2x≥2-2x \ge 2

x≤−1x \le -1

You can also collect the xx terms on the right, toward the 5x5x. Then the coefficient is positive and there is no flip. You end with −1≥x-1 \ge x, which reads as x≤−1x \le -1. Both ways give the same answer. One way has a flip and the other has a swap of sides at the end. No way has both.

Before you start, count the parts of the inequality: a bracket, xx terms on both sides, numbers on both sides. Then you need four steps: open the bracket, collect the xx terms, collect the numbers, and divide. At each step, ask whether it flips the sign. Only multiplying or dividing by a negative number does.

challenge icon

Challenge

Hard

Solve the inequality 2(x+1)−3x<x+102\left(x+1\right)-3x < x+10 for xx.

Try it yourself

2(x+1)−3x<x+102\left(x+1\right)-3x < x+10

Get xx alone on one side

All lessons in Inequalities & Absolute Value