I've got these two problems which I can't seem to figure out. I've tried different ways of doing them but none give me the correct answer.

Here is the first problem

f(x) = 6.0 - 8.0x^{2}; find f(9.0 x 10.0) - [9.0f(10.0)]^{2}

And the second

A conical sheet metal hood is to cover an area 1.0 m in diameter. What is the surface area of the hood if its height is 8.0?

There are a number of questions similar to the first, so I'm hoping once I figure out how to do this one the others will make more sense.

Thanks for any help!