Tom K. answered 04/18/21
Knowledgeable and Friendly Math and Statistics Tutor
Think Maclaurin.
f(t) = f(0)+f'0)t + f''(0)t^2/2! + f'''0)t^3/3!, as f''''(t) = 0 for all t
f(0) = 10
f'(0) = 0
f''(x) = 10 - t, so f''(0) = 10 and f'''(t) = -1 for all t
f(t) = 10+ 0t + 10t^2/2! + -1t^3/3!
f(t) = 10 + 5t^2 -t^3/6
f(20) = 10 + 5 * 20^2 - 20^3/6 = 10 + 2000 - 8000/6 = 676 2/3