When you multiply a nonzero rational and an irrational number, the outcome is irrational. It's a pretty advanced proof, having to do with a contradiction theorem. For example, 2*e is irrational.
Rewrite it in the form a^2 - b^2, where a = x and b = 5
x^2 - 5^2
Use the Difference of Squares: a^2 - b^2 = (a + b)(a - b)
<u>= (x + 5)(x - 5)</u>
The awnser is D. It's correct.
