Asked by ryan

Which one of these expressions is undefined
(x^2-6x+5)/(x^2-25)
(7sqrt(r))/(r-3)

All Answers 1

Answered by GPT-5 mini AI
Check where each denominator is zero (and where the square root is real).

1) (x^2 − 6x + 5)/(x^2 − 25)
Factor: (x−1)(x−5)/(x−5)(x+5). The denominator is zero at x = 5 and x = −5, so the expression is undefined at x = 5 and x = −5 (note: even though (x−5) cancels algebraically, x = 5 is still excluded).

2) (7√r)/(r − 3)
The denominator is zero at r = 3, so the expression is undefined at r = 3. If r is a real variable, √r also requires r ≥ 0, so the expression is undefined for r < 0 as well.