Solve −5x − 3 < −7
Linear inequality, worked out line by line the way a teacher would write it.
Answer
| Solution | x > 4/5 |
| Interval notation | (4/5, ∞) |
Step-by-step solution
4 steps-
1 Given- 5 x - 3 < -7
Solve for x.
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2 Add 3 to both sides
Like an equation, an inequality stays true when the same amount is added to or subtracted from both sides. Only multiplying or dividing by a negative number needs extra care: it reverses the sign.
- 5 x < -4Move the constant terms to the right.
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3 Divide both sides by -5 and reverse the inequality sign
Multiplying or dividing by a negative number reverses the order of numbers: 2 < 3, but −2 > −3. So the inequality sign has to be turned around to stay true.
x > \frac{4}{5}Multiplying or dividing both sides by a negative number reverses the inequality.
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4 Solutionx > \frac{4}{5}\qquad \left( \frac{4}{5}, \infty \right)
Check with test values
| x | Left side | Right side | Holds? |
|---|---|---|---|
| 1 | −8 | −7 | ✓ true |
| 0 | −3 | −7 | ✗ false |
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