00:01
For this problem, we are asked to find the maximum and minimum values of x squared plus y squared, subject to the constraint, x squared minus 2x plus y squared minus 4y, equals 0.
00:11
To begin, we take the partial derivative of our original function with respect to x, which gives us 2x, and that must be equal to lambda times the partial derivative of the constraint with respect to x.
00:22
So we have lambda times 2x minus 2, which then gives us that lambda must be equal to 2x, over 2x minus 2.
00:33
Or dividing numerator and denominator by 2, we get that lambda must be equal to x over x minus 1.
00:39
Then, with respect to y, we get 2y must be equal to lambda times 2y minus 4, which then gives us that lambda must be equal to 2y over 2y minus 4, which then will be equal to y over y minus 2.
00:57
We also then have that x over x minus 1 must be equal to y over y minus two.
01:05
Multiplying both sides by x minus 1 times y minus 2 gives us, well, we'd have xy minus 2x must be equal to xy minus y...