Help evaluating an expression

It's embarrassing that I can be thrown off by such a seemingly simple question, but I really cannot understand why one of my methods isn't working.

Question: Evaluate 9x^{2}y+3y^{4 }when x=4 and y=-2. When I do ((9**4*^{2})-2)+(3*-2^{4}) I get -336 but the correct answer is -240.

When I use the graphic calculator and just store x as 4 and y as -2 it gives me the -240. Help? :(

Re: Help evaluating an expression

Hi There,

I’ve managed to get -240 by doing this:

9x^{2}y + 3y^{4}

When x=4 and y=-2 then:

= 9*4^{2}*-2 + 3*-2^{4}

= 9*16*-2 + 3*16

= -288 + 48

= -240

Hope this helps?

Re: Help evaluating an expression

Thanks a lot. :D I needed the (-2)^{4} as (-2^{4}) is wrong obviously. Don't know how I missed.