Question

Coonsideram functia f : R⇒R , f ( x ) = 2x + 1 . Calculati suma S = f ( -2 ) + f (-1 ) + f ( 0 ) +f ( 1 ) + f ( 2 ) . MULTUMESC

Answer 1

$S = f ( -2 ) + f (-1 ) + f ( 0 ) +f ( 1 ) + f ( 2 )$⇔
$S =[2*(-2)+1]+[2*(-1)+1][2*(0)+1][2*(1)+1][2*(2)+1]$⇔
$S=2*[(-2)+(-1)+0+1+2]+(1+1+1+1)$⇔
$S=2*0+4*1$⇔$S=0+4$⇒$S=4$

Answer 2

f(-2) = -4 +1 = -3   
f(-1) = -2 +1= -1
f(0) = 1
f(1) = 2+1 =3
f(2) = 4+1 =5

S= -3 + (-1) +1 + 3 + 5 = 5