The question
Ana wrote (x + 5)² − 25 = x² + 10x + 25. Which is correct?
Ana wrote (x + 5)² − 25 = x² + 10x + 25. Which is correct?
(x + 5)² − 25
(x + 5)² − 25=x² + 10x + 25 − 25
(x + 5)² − 25=x² + 10x + 25 − 25
(x + 5)² − 25=x² + 10x
(x + 5)² − 25=x² + 10x
they wrote:x² + 10x + 25
- Do not check by reading their line. Somebody else's working is the most persuasive thing on the page, and rereading it is how you end up agreeing with it — do the step yourself first, then compare.
- On your own, and writing the step nobody writes down: (x + 5)² − 25 becomes x² + 10x + 25 − 25.
- Tidy that up and it is x² + 10x.
- Now compare. They wrote x² + 10x + 25, and the squared constant was never taken away again — so the correct answer is x² + 10x.
How it works.
- 01
Do not check by reading their line. Somebody else's working is the most persuasive thing on the page, and rereading it is how you end up agreeing with it — do the step yourself first, then compare.
- 02
On your own, and writing the step nobody writes down: (x + 5)² − 25 becomes x² + 10x + 25 − 25.
- 03
Tidy that up and it is x² + 10x.
- 04
Now compare. They wrote x² + 10x + 25, and the squared constant was never taken away again — so the correct answer is x² + 10x.