Wize High School Grade 12 Calculus Textbook > Rate of Change

Evaluating 00\frac{0}{0} Limits -- by Factoring

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Example: Factoring 0/0 Limits

Evaluate limx2 x24x2\displaystyle\lim_{x\to2}\ \frac{x^2-4}{x-2}.

Direct substituteion gives us 00\frac{0}{0}, try factoring:

limx2(x+2)(x2)x2\displaystyle\lim_{x\rightarrow2}\frac{\left(x+2\right)\left(x-2\right)}{x-2}
=limx2x+2\displaystyle=\lim_{x\rightarrow2}x+2
=4=4

Practice: Factoring 0/0 Limits

limh0 4(5h+2)2h=\displaystyle\lim_{h\to0}\ \frac{4-\left(5h+2\right)^2}{h}=

Practice: 0/0 Limit

Evaluate limt1 3t31t\displaystyle\lim_{t\to1}\ \frac{\frac{3}{t}-3}{1-t}, if it exists.