Ta có:\(M=x^4-xy^3+x^3y-y^4-1\)
\(M=\left(x^4-y^4\right)-\left(xy^3-x^3y\right)-1\)
\(M=\left(x^4-y^4\right)-xy\left(y^2-x^2\right)-1\)
Mà x+y=0
\(\Rightarrow x=-y\)
\(\Rightarrow M=\left[\left(-y\right)^4-y^4\right]-xy\left[y^2-\left(-y\right)^2\right]-1\)
\(M=\left(y^4-y^4\right)-xy\left(y^2-y^2\right)-1\)
\(M=0-0-1\)
\(M=-1\)
Ta có: x+y=0=> x=0; y=0
\(\Rightarrow M=x^4-x\times y^3+x^3\times y-y^4-1\)
\(\Rightarrow M=\left[x^4-\left(x^3+x\right)\right].\left[y^4-\left(y^3+y\right)\right]-1\)
\(\Rightarrow M=\left[x^4-x^4\right]\times\left[y^4-y^4\right]-1\)
\(\Rightarrow M=0\times0-1\)
\(\Rightarrow M=-1\)
Vậy M=-1
Choa ko chắc đâu nha
