Ta có: \(M+\left(5x^2-2y^3\right)=10x^2+4y^3\)
=>\(M=\left(10x^2+4y^3\right)-\left(5x^2-2y^3\right)=10x^2+4y^3-5x^2+2y^3\)
\(=\left(10x^2-5x^2\right)+\left(4y^3+2y^3\right)=5x^2+6y^3\)
Mặt khác \(M+N=8x^2-3y^2\)
\(\Rightarrow N=\left(8x^2-3y^2\right)-M=\left(8x^2-3y^2\right)-\left(5x^2+6y^3\right)\)
\(=8x^2-3y^2-5x^2-6y^3=3x^2-6y^3-3y^2\)
Vậy N=3x2-6y3-3y2
M+(5x2-2y3)=10x2+4y3
=>M=10x2+4y3-5x2-2y3
=>M=(10x2-5x2)+(4y3-2y3)
=>M=5x2+2y3
=>N=8x2-3y2-5x2-2y3
=>N=3x2-3y2-2y3