equation of a line

Question

what is the value of expression 2x^2+3xy-4y^2when x=2 and y=-4 ?

Answer 1

The expression is 2x² + 3xy - 4y²

Substitute the values x = 2 and y = - 4 in above expression.

= 2(2)² + 3(2)(- 4) - 4(- 4)²

= 8 - 24 - 64

= - 80

The value of the expression is - 80 when x = 2 and y = - 4.