Solve for x: sqrt(5x – 4) = 6.

Explanation

• Square both sides to clear the root: 5x − 4 = 6² = 36.
• Solve what is left: 5x = 40, so x = 8.
• Substitute to verify: √(5 × 8 − 4) = √36 = 6, which matches the question.
• Always test your answer in the original equation, because squaring can create values that do not really work.
• The expression under a square root cannot be negative, so 5x − 4 ≥ 0 means x must be at least 0.8.