algebra 2 problem

Question

(x)=x^5-x^4+6x^3-4x^2-18x+8; [1.6, 1.9]

 

I tried and tried but I can’t find the value of f (1.6) and (1.9)

Answer 1

f(1.6) = (1.6)⁵ - (1.6)⁴ + 6(1.6)³ - 4(1.6)² - 18(1.6) + 8

 

         = -2.53184

 

f(1.9) is found in a similar manner