Sagot :
[tex]( 3x + x ^2) - (4x^2 - 3x +(2x^2 - x - (5x^2 + 4x)))=\\
3x+x^2-4x^2+3x-(2x^2-x-5x^2-4x)=\\
-3x^2+6x-2x^2+x+5x^2+4x=\\
11x[/tex]
[tex](3x+x^2)-\{4x^2-3x+[2x^2-x-(5x^2+4x)]\}\\\\=3x+x^2-\{4x^2-3x+[2x^2-x-5x^2-4x]\}\\\\=3x+x^2-\{4x^2-3x+[-3x^2-5x]\}\\\\=3x+x^2-\{4x^2-3x-3x^2-5x\}\\\\=3x+x^2-\{x^2-8x\}\\\\=3x+x^2-x^2+8x\\\\=11x[/tex]