Mathematics

Problem

Let

p(x)=\dfrac{1}{x^2-7x+10}

q(x)=\dfrac{x}{x^2-9}

and

r(x)=\dfrac{x-2}{x^2-2x-15}

. How many distinct real numbers must be excluded from the domains of the three functions taken together? a) 6 b) 3 c) 4 d) 5