Odpowiedź:
[tex]13x^2+2x+(-13x^2)=13x^2+2x-13x^2=2x\\\\x^2-5x^2+7x^2=8x^2-5x^2=3x^2\\\\x-x-2x+x=-2x+x=-x\\\\x+3x^2-x+(-5x^2)=3x^2-5x^2=-2x^2\\\\3x-7x+5x=8x-7x=x\\\\-x^2-x^2-x^2=-3x^2\\\\4x+x^2+x^2-4x=x^2+x^2=2x^2\\\\12x+x-15x=13x-15x=-2x[/tex]
