Solve the equation √(4x + 3) = 4 for x.

Correct answer: 13/4. Squaring both sides gives 4x + 3 = 16, so 4x = 13 and x = 13/4.

Background: Squaring removes the square root.

• 19/4: x = 19/4 gives √22, not 4.
• 16: x = 16 gives √67, not 4.
• 12: x = 12 gives √51, not 4.

Did you know? Check: 4 × 13/4 + 3 = 16 and √16 = 4.

Memory trick: Square both sides first.