Melody

It is still there.

Can you give me a link to your graph?  I mean your graph of B which is the one you think might be the answer.

By the way,

I am still waiting for you to answer my question on this thread.

Hi PC

Graph them on this calculator and see for yourself.  Then try to figure out why.

Philip ran out of time while taking a multiple-choice test and plans to guess on the last 4 questions. Each question has 5 possible choices, one of which is correct.  Assume that the results of his guesses are independent. What is the probability that he answers exactly 1 question correctly in the last 4 questions?

P(correct)=0.2

P(exactly one out of 4 correct) = 4C1*0.2*0.8^3 = 4*0.2*0.512 = 0.4096

If you had titled you question something relevant,   like  "Physics, conductivity of copper wire."

You would have been more likely to attract the attention of a physicist. 

Thanks Tiggsy,

I thought there was probably a better way. Or at least a way that did not involve graphing or calculus.  :)

x and y will not be equal

I do not believe that the answer is 16/3

I gave you an answer, I do not see your thanks.

It is easy enough to get an exact answer using calculus.

\(x=\sqrt{16-2y^2}\\ let \;\;M=xy\\ M=y*\sqrt{16-2y^2}\\ Find \quad dM/dy\\ \text{put it equal to 0 to find the stationary points.}\\ \text{Solve for y}\\ \text{Substitute to find M}\\ \text{if you are feeling keen you should prove that this is a maximum.}\\ \text {This will give you the exact value that i have already approximated via the graph.}\\ \)