Question

Evaluate each function at the given value. 1) f (x) = x3 − x2 − 25x + 35 at x = −5 2) f (n) = −4n4 − 13n3 − 5n2 + 16n + 18 at n = −2

Answer 1

a) f(-5) =10

b) f(-2) = 26

Explanation:

Given that the function

f (x) = x³ − x² − 25x + 35

Put x =-5

f(-5) = (-5)³ - (-5)²-25(-5)+35

= -125-25+125+35

= 10

f(-5) =10

ii)

f(n) = -4n⁴ - 13n³-5n²+16n+18

f(-2) = -4(-2)⁴ -13(-2)³-5(-2)²+16(-2)+18

= -4(16)-13(-8)-5(4)-12+18

= -64 +104-20-12+18

= 122-96

= 26

f(-2) = 26