for this question first i identified (r+1)^2 = r^2+2r+1

i subbed in r+1 into r which gave me f(r+1)= 2r^3 + 8r^2 + 13r + 6

then subtracted the expanded version of f(r) which is 2r^3 + 3r^2 + r

which at the end gave me 5r^2 + 12r + 6

i think the 5 in my answer should be 6

spot my mistake please.

YEEEEEET Dec 29, 2018

#1**0 **

You are correct in your assumption.....

instead of 2 r^3 + 8r^2 + 13 r + 6 I get

2 r^3 +** 9**r^2 + 13r + 6 ....... So when you were expanding, you got something a little befuzzled.....look at it again....G'Luck !

ElectricPavlov Dec 29, 2018