solve for f (-2) if...

Question

if f(x)=   5

             ∑    (ix + i² ),  then f(-2)= ?

             i=2

Answer 1

Hi Judy,

 

ix + i² = i(x + i)

when

i=2, 2(-2+2) = 0

i=3, 3(-2+3) = 3

i=4, 4(-2+4) = 8

i=5, 5(-2+5) = 15

 

sum = 15+8+3

= 26