I believe the answer would be a(a-4)(a-13)
I started with the a^3 - 17a^2 + 52a and factored out an "a"
---> a(a^2 - 17a +52)
Then I factored the expression in parentheses (*To factor it, you need to find out what multiplies to become 52 and adds to become 17*) And you get -4 and -13
---> a(a-4)(a-13)