Question

Se considera f : R -> R,f( x ) = -2x+6
Calculati suma f(1)+f(2)+…+f(50)

Answer 1

Răspuns:

Explicație pas cu pas:

f(x) = -2x + 6

f(1) = -2 + 6 = 4

f(2) = -4 + 6 = 2

f(3) = -6 + 6 = 0

f(4) = -8 + 6 = -2

f(5) = -10 + 6 = -4

............

f(50) = -100 + 6 = -94

S = 4 + 2 + 0 - 2 - 4 - 6 - 8 - 10 -.....- 94

= -6 - 8 - 10 - ...- 94 = -2*(3 + 4 + 5 + ...+ 47) = -2*47*48/2 = -2256