Question 359055
You can only add like terms.
{{{ (3x^2-2xy+y^2)+(-6x^2-7xy-y^2)+(x^2+xy-4y^2)=(3x^2-6x^2+x^2)+( -2xy-7xy+xy)+(y^2-y^2-4y^2) }}}
{{{ (3x^2-2xy+y^2)+(-6x^2-7xy-y^2)+(x^2+xy-4y^2)=(3-6+1)x^2+( -2-7+1)xy+(1-1-4)y^2 }}}
Complete the calculation to get the solution.