I'm completely stuck on the following problem:

I have included my work below but as I worked the problem down I seemed to be way off from the solution. The solution I pulled from Slader.

Link: https://www.slader.com/textbook/9780538497831-stewart-single-variable-calculus-7th-edition/507/exercises/25/

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What am I doing wrong? A step through would be really appreciated.


1 Answer 1


It appears that you've made a small calculation error when calculating the value for $c$ when using the pythagorean theorem (second image).

The correct expansion is $(2x+1)^2=4x^2+4x+\mathbf{1}$, where you wrote $4x^2+4x+\mathbf{2}$.

Just as a side note, it would be greatly preferred if you use mathjax or an alternative rather than uploading a plain picture of your work. I understand that it's pretty time consuming and sometimes frustrating to type up everything, but it was pretty difficult to read some of your work.

Perhaps you could use an app like Genius Scan to make your images clearer?

  • $\begingroup$ thank you! I will take pictures with better lighting next time and get improved images; appreciate your suggestion $\endgroup$
    – PineNuts0
    Mar 7, 2020 at 17:31
  • 2
    $\begingroup$ Hadi, if you want people to be better about good posting etiquette, you can't give them an answer before they cleanup their question. I know I'm always eager to share my answer, and so it can be hard for me to wait to respond, but that's how they'll improve. $\endgroup$
    – JonathanZ
    Mar 7, 2020 at 18:11

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