4
Let the two integers be denoted by $x$ and $y$.
We can use the algebraic identity relating the sum, product, and difference of two numbers:
$ (x - y)^2 = (x + y)^2 - 4xy $
Substitute the given values into the identity:
$ (x - y)^2 = (26)^2 - 4(165) $
Calculate the terms:
$ (26)^2 = 676 $
$ 4 \times 165 = 660 $
Now, compute $(x - y)^2$:
$ (x - y)^2 = 676 - 660 $
$ (x - y)^2 = 16 $
To find the difference, take the square root of both sides:
$ x - y = \sqrt{16} $
$ x - y = \pm 4 $
The difference between the two integers is $4$.
Given $f(x, y) = x^2 - 2xy + y^2$
The complete contour of the equation $f(x, y) = 1$ is described by the option(s) ___.