Question

Fie functia f:R->R,f(x)=2x-4.
Calculati f(1)+f(2)+f(3)+f(4)+f(5)+f(6).

Answer 1

f(x)=2x-4
f(1)=2-4=-2
f(2)=4-4=0
f(3)=6-4=2
f(4)=8-4=4
f(5)=10-4=6
f(6)=12-4=8

Deci f(1)+f(2)+f(3)+f(4)+f(5)+f(6).=
-2+0+2+4+6+8 = 18