Chapter 12: Q. 8 (page 989)

Evaluate the following limits, or explain why the limit does not exist.
$\lim_{(x, y) \to (0, 0)} \frac{x + y}{x^{2} + y^{2}}$

Short Answer

Expert verified

$\lim_{(x, y) \to (0, 0)} \frac{x + y}{x^{2} + y^{2}} = \infty (does not exist)$

Step by step solution

Step 1. Given information is:

$\lim_{(x, y) \to (0, 0)} \frac{x + y}{x^{2} + y^{2}}$

Step 2. Evaluating Limits

$Since, (x, y) \to (0, 0) x + y = 0 and x^{2} + y^{2} = 0 So to find \lim_{(x, y) \to (0, 0)} \frac{x + y}{x^{2} + y^{2}}, take x = r cosθ and y = r sinθ then, (x, y) \to (0, 0) when r \to 0 Now, \frac{x + y}{x^{2} + y^{2}} = \frac{rcosθ + rsinθ}{r^{2} \cos^{2} θ + r^{2} \sin^{2} θ} = \frac{cosθ + sinθ}{r} Therefore, \lim_{(x, y) \to (0, 0)} \frac{x + y}{x^{2} + y^{2}} = \lim_{r \to 0} [\frac{cosθ + sinθ}{r}] = \infty Hence, \lim_{(x, y) \to (0, 0)} \frac{x + y}{x^{2} + y^{2}} = \infty (does not exist)$

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Evaluate the following limits, or explain why the limit does not exist.
$\lim_{(x, y) \to (0, 0)} \frac{x + y}{x^{2} + y^{2}}$

Short Answer

Step by step solution

Step 1. Given information is:

Step 2. Evaluating Limits

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Evaluate the following limits, or explain why the limit does not exist.lim(x,y)→(0,0)x+yx2+y2

Short Answer

Step by step solution

Step 1. Given information is:

Step 2. Evaluating Limits

One App. One Place for Learning.

Most popular questions from this chapter

Recommended explanations on Math Textbooks

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Study anywhere. Anytime. Across all devices.

Evaluate the following limits, or explain why the limit does not exist.
$\lim_{(x, y) \to (0, 0)} \frac{x + y}{x^{2} + y^{2}}$