Question

What is the value of the expression 2x2 3xy – 4y2when x = 2 and y = –4? a. –80 b. –32 c. 32 d. 80

Answer 1

2x^2 + 3xy - 4y^2 when x = 2 and y = -4
= 2(2)^2 + 3(2)(-4) - 4(-4)^2 = 2(4) + (-24) - 4(16) = 8 - 24 - 64 = -80