I tutor an AP Calculus AB class at the library every week, and I recently gave the students a test on Limits and Continuity. The test was fairly straightforward, but some of the free-response questions were somewhat difficult. The students seemed to get the answers fine, but my friend/mentor seemed to disagree with the answer to one of the questions.(adsbygoogle = window.adsbygoogle || []).push({});

The problem in question is the following limits question: [itex]lim_{x→0}[/itex] [itex]\frac{\sqrt{ax + b} – 2}{x} = 1[/itex]

Given this equality, students were asked to find the values ofaandb.

My solutions werea= 4 andb= 4. However, this was disputed by my friend/mentor, who claimed that ifx≠ 0.

Can somebody settle this dispute? What are the values ofaandb?

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