Question

Sendo f(x)=5x² - 11x + 2, determine
a) f(-1)
b) f( 1/5)
c) f(7/5)
Obs: b,c são frações

Answer 1

f(x) = 5x² - 11.x + 2

a) f(-1) = 5.(-1)² - 11.(-1) + 2
f(-1) = 5.1 + 11 + 2
f(-1) = 18

b) f(1/5) = 5(1/5)² - 11.(1/5) + 2
f(1/5) = 5.(1/25) - 11/5 + 2
f(1/5) = 5/25 - 11/5 + 2
f(1/5) = 1/5 - 11/5 + 2
f(1/5) = (1 - 11 + 10)/5
f(1/5) = (-10 + 10)/5
f(1/5) = 0

c) f(7/5) = 5.(7/5)² - 11.(7/5) + 2
f(7/5) = 5(49/25) - 77/5 + 2
f(7/5) = 49/5 - 77/5 + 2
f(7/5) = (49 - 77 + 10)/5
f(7/5) =  -18/5

Espero ter ajudado.