- #1
sinbad30
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Homework Statement
Applying the definition of a limit to show that
lim ((x^3 * y(y-1) ) / (x^2 + (y-1)^2) = 0 as (x,y) approaches (0,1)
The Attempt at a Solution
|x| = sqrt(x^2) <= sqrt((x^2 + (y-1)^2))
|y-1|=sqrt((y-1)^2)<= sqrt((x^2 + (y-1)^2))
|y|<= |y-1| + 1 via the triangle inequality
Let e>0. We want to find d>0 such that
0 < sqrt((x^2 + (y-1)^2)) < d then (|x|^3 |y| |y-1|)/ (x^2 + (y-1)^2) < e
So
(|x|^3 |y| |y-1|)/ (x^2 + (y-1)^2) <=
[(sqrt((x^2 + (y-1)^2)))^3 * sqrt((x^2 + (y-1)^2)) * (sqrt((x^2 + (y-1)^2)) + 1) ] / (x^2 + (y-1)^2)
Any ideas as to how to break down the right side of the inequality?