Worked example
Check x = 3 for √(x + 6) = x
- The domain requires x ≥ 0.
- Left side: √(3 + 6) = 3.
- Right side: 3.
- Both sides match, so x = 3 is valid.
Math guide
Check the original question, not only your last line.
Put a proposed solution into the original equation and verify the domain, both sides and any extraneous roots.
Replace the variable in the original equation with the proposed value. Evaluate each side independently, confirm the value is allowed by the domain, and reject any candidate that does not make the original statement true.
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