What is the domain of the function \(f(x)=\log_2(x^2-5x+6)\)?

Correct answer: \((-\infty,2)\cup(3,\infty)\)

The argument of a logarithm must be strictly positive, so \(x^2-5x+6>0\). Factoring gives \((x-2)(x-3)>0\), which holds when \(x<2\) or \(x>3\). Therefore, the domain is \((-\infty,2)\cup(3,\infty)\). Option B is incorrect because the logarithm's argument is negative between 2 and 3; the endpoints are also excluded because the argument becomes zero there. Exam tip: For \(\log_a(g(x))\), always impose \(g(x)>0\), not merely \(g(x)\ne0\).