Question 252911
{{{2x^2+3xy-4y^2}}} Start with the given expression.



{{{2(2)^2+3(2)(-4)-4(-4)^2}}} Plug in {{{x=2}}} and {{{y=-4}}}



{{{2(4)+3(2)(-4)-4(16)}}} Square 2 to get 4 and square -4 to get 16



{{{8-24-64}}} Multiply



{{{-80}}} Combine like terms.



So {{{2x^2+3xy-4y^2=-80}}} when {{{x=2}}} and {{{y=-4}}}