Question 171482
{{{(-7x^2 + 5xy - 2y^2) + (3x^2 - 5xy - 4y^2)}}} Start with the given expression



{{{-7x^2 + 5xy - 2y^2 + 3x^2 - 5xy - 4y^2}}} Remove the parenthesis.



{{{(-7x^2+3x^2)+(5xy-5xy)+(-2y^2-4y^2)}}} Group like terms



{{{-4x^2-6y^2}}} Combine like terms



So {{{(-7x^2 + 5xy - 2y^2) + (3x^2 - 5xy - 4y^2)=-4x^2-6y^2}}}