Limits at Infinity, Part I — Question 6

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Question 6

Evaluate the limit: limx→∞3x5−2x2+1x5+4x3−x\lim_{x \to \infty} \frac{3x^5 - 2x^2 + 1}{x^5 + 4x^3 - x}

Original worksheet page 1: question and worked solution for 2-7-006
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Question 6 - Solution

We are given: limx→∞3x5−2x2+1x5+4x3−x\lim_{x \to \infty} \frac{3x^5 - 2x^2 + 1}{x^5 + 4x^3 - x}

Step 1: Divide numerator and denominator by the highest power of xx, which is x5x^5: =limx→∞3−2x3+1x51+4x2−1x4= \lim_{x \to \infty} \frac{3 - \frac{2}{x^3} + \frac{1}{x^5}}{1 + \frac{4}{x^2} - \frac{1}{x^4}}

Step 2: As x→∞x \to \infty, all terms with negative powers of xx go to zero: =3−0+01+0−0=3= \frac{3 - 0 + 0}{1 + 0 - 0} = \boxed{3}

Original worksheet page 2: question and worked solution for 2-7-006

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