Question

Se considera functia f:R-R,f(x)=2x-5
a) sa se calculeze suma f(3) +f(3 la 2 )+...+f(3 la 5)

Answer 1

F (x)=2x-5

F (3)+F (3^2)+..+F (3^5)=

=2×3-5+2×3^2 -5+..+2×3^5 -5

=2 (3+3^2 +..+3^5)-5×5

3+3^2+..+3^n=(3^(n+1) -3)/2

=2×[(3^6 -3)/2] -25

=2×(726/2)-25

=726-25

=701