Need help figuring out problem on a practice test for school

[a6303e]

How do I figure out:

2x^2 + 3xy - 4y^2

x=2 and y=-4

Thank you

 

[arthur ohlsten]

the question you are being asked is." What is the value of 2x^2+3xy-4y^2, when x=2 and y=-4
substitute 2 for x and -4 for y
2x^2+3xy-4y^2
2[2]^2+3[2][-4]-4[-4]^2
8-24-64
-80

Arthur

 

[Denis]

Re: Need help figuring out problem on a practice test for sc

How do I figure out:
2x^2 + 3xy - 4y^2
x=2 and y=-4

REMEMBER: 3xy simply means 3 times x times y ; so: 3 times 2 times -4

x^2 means x squared or x times x