Consider the function g(x)=59x. Observe that g(1)=59, g(2)=118, and g(3)=177, from which it follows that
f(1)=g(1), f(2)=g(2), and f(3)=g(3).
Now define a polynomial h(x)=f(x)−g(x) so that, by construction,
x=1, x=2, and x=3 are roots of h(x).
Algebraically, we also have that h(x)=f(x)−g(x)=x4+px3+qx2+rx+s−59x=x4+px3+qx2+(r−59)x+s but the important thing to notice here is that h(x) is a degree four polynomial with a
leading coefficient of 1.
Since we already know that x=1,
x=2, and x=3 are roots of h(x), we conclude that h(x)=(x−1)(x−2)(x−3)k(x) for some
polynomial k(x). However, because
h(x) has degree 4 and a leading coefficient of 1, it must be true that k(x) has degree 1 and a leading coefficient of 1.
Thus, h(x)=(x−1)(x−2)(x−3)(x−a)
for some real number a.
We now evaluate h(x) at x=9 and x=−5 to get h(9)h(−5)=(9−1)(9−2)(9−3)(9−a)=336(9−a)=(−5−1)(−5−2)(−5−3)(−5−a)=336(5+a)
Now using that h(x)=f(x)−g(x) or
f(x)=h(x)+g(x), we can determine
the value of f(9)+f(−5) as follows:
f(9)+f(−5)=h(9)+g(9)+h(−5)+g(−5)=336(9−a)+9(59)+336(5+a)−5(59)=336(9)−336a+9(59)+336(5)+336a−5(59)=336(9+5)+59(9−5)=336(14)+59(4)=4940 Therefore, T=4940, so the answer is 4+9+4+0=17.