What is the product of the solutions to ?
Show the answer and explanation
Why A is right
Squaring both sides yields = , which rearranges to - . This factors as , giving or . Checking : , which equals x, so is valid. Checking : , but , so this is extraneous. Only is a valid solution, and the product of the valid solutions is 4.
Why the others are wrong
- BThis results from a sign error in the constant term when rearranging the squared equation or misapplying Vieta's formulas.
- CThis is the product of both algebraic solutions from the factored form (4 × (-1) with a sign error or 4 × 4 from repeating the valid root), including computation errors.
- DThis results from finding only one of the algebraic roots or miscounting which solutions are valid after checking.