Question

Fie funcția f:R->R, f(x)=5-x. Să se calculeze :
a) f(1)+ f(2)+...+f(100)
b)f(1)* f(2)*...* f(100)

Answer 1

Explicație pas cu pas:

a)

f(1)=4

f(2)=3

f(100)=-95

S=f(1)+ f(2)+...+f(100)

S=4+3+...+(-95)

n=(-95-4)/1+1=-98

S=-98(-95+4)/2=-98*(-91)/2=49*91=4459.

b)

S=f(1)*f(2)*f(3)*f(4)*f(5)*...*f(100)

f(3)=2

f(4)=1

f(5)=0

S=4*3*2*1*0*...*(-95)=>S=0.

Bafta!