Question

What is the domain of the function y = (x^2-25)/(x-5)?
a (- ∞, +∞)
b {x I x ≠5}
c {x I x ≠-5 }
d [0,5]

Answer 1

whats your guess ?

Answer 2

You can factor the numerator by the difference of two squares rule:
\[a ^{2} − b ^{2} = (a + b)(a − b)\]
You don't really need too here, but it can be helpful to in some cases. Note that even after you factor and simplify, you still have to account for the fact that original denominator was (x-5), and dividing by zero is undefined.

Answer 3

\[(x^2 - 25 )/ (x-5)\]