Question

C/m:

\(x^4+y^4+\left(x+y\right)^4=2\left(x^2+xy+y^2\right)^2\)

Answer 1

aaaaaaaaaaaaaaa

aaaaaaaaaaaaaaa

aaaaaaaaaaaaaaa

Answer 2

379+920=

Answer 3

Sử dụng khai triển nhị thức Newton:

\(\left(x+y\right)^4=x^4+4x^3y+6x^2y^2+4xy^3+y^4\)

\(\Rightarrow x^4+y^4+\left(x+y\right)^4=2x^4+4x^3y+6x^2y^2+4xy^3+2x^4=2\left(x^4+2x^3y+3x^2y^2+2xy^3+y^4\right)\)

Khai triển:\(2\left(x^2+xy+y^2\right)^2=2\left(x^4+x^2y^2+y^4+2x^3y+2xy^3+2x^2y^2\right)=2\left(x^4+2x^3y+3x^2y^2+2xy^3+y^4\right)\)

\(\Rightarrowđpcm\)