Folosim formula:
[tex] a^{3} - b^{3} = ( a-b )*( a^{2} + a*b + b^{2} ) [/tex]
[tex] x^{3} - (2x-y)^{3} =[/tex]
[tex] = [ x - (2x-y)]*( x^{2} + x*(2x-y)+(2x-y)^{2} ]= [/tex]
[tex] = ( x - 2x+y)*( x^{2} + 2 x^{2} -x*y + 4*x^{2}-4*x*y+ y^{2} )= [/tex]
[tex] = ( y-x)*( 7* x^{2} -5*x*y + y^{2} ) [/tex]
Sper ca nu am gresit la calcule. Daca da, voi corecta.
