Question

Use the binomial theorem to find expressions in terms of r1 and r2 for:
i. (x^3+y^3) ii. (x^4+y^4)
r1=(x+y) and r2=(xy)

Answer 1

could you help me with the working? I have no idea how to get the answer :(

Answer 2

do you know
\[(x ^{3}+y ^{3})=(x+y)(x ^{2}+y ^{2}-xy)\]

Answer 3

do you know that formula?

Answer 4

yes, but i have to use the binomial theorem, for ii

Answer 5

@midhun.madhu1987

Answer 6

@aryandecoolest

Answer 7

@agreene

Answer 8

@ganeshie8

Answer 9

@hopelovelift

Answer 10

1. (r1)(r1^2-3r2)

Answer 11

2. r1^4-4r2( r1^2-2r2)-6r2^2

Answer 12

ok that looks good thanks :) do you have any working? I would really like to know how you worked it out :)

Answer 13

well yeah i have working.!!!

Answer 14

hope first one is clear to you. right?

Answer 15

yeah the fist one is clear, but I do not know how to use the binomial theorem, could you post the working? thanks

Answer 16

\[(x+y)^4=4C _{0}*x^4+4C _{1}*x^3y+4C _{2} *x^2y^2+4C _{3} *xy^3+4C _{4}*y^4\]
\[x^4+y^4=(x+y)^4-4x^3y-4xy^3-6(xy)^2\]
substitute and get the answer )

Answer 17

thanks! :)

Answer 18

np ) anytime