Question 83225
Line up the equations vertically

{{{5x^2+2x-4}}}
{{{x^2-2x-3}}}
{{{2x^2-4x-3}}}


Notice how the x squared terms make a column, the x terms make a column, and the constant terms make a column. Add these columns separately


{{{5x^2+x^2+2x^2=8x^2}}} Add the x squared terms


{{{2x-2x-4x=-4x}}} Add the x terms


{{{-4-3-3=-10}}} Add the constant terms


So after adding we get


{{{8x^2-4x-10}}}