Question

f:R - R
f(x)=-3x+2
Determinati numatul real a, daca,
f(a-1)+f(a)+f(a+1)=0

Answer 1

f(a-1)=-3(a-1)+2=-3a+3+2=-3a+5
f(a)=-3a+2
f(a+1)=-3(a+1)+2=-3a-3+2=-3a-1

f(a-1)+f(a)+f(a+1)=0⇔
-3a+5-3a+2-3a-1=0⇔
-9a+6=0⇔
-9a=-6⇔
a=-6/(-9)=2/3