More expanding and simplifying and finding volume

1)Expand and simplify

$\displaystyle n^2+(n-1)^2$ I got $\displaystyle n^4-2n+1$????

If n is a whole number show that this expression must be an odd number. From my previous post would this be the answer: (3n)(76)

2)The radius of a sphere is 3y cm

The radius of a cylinder is 2y cm and the cylinder's height is H cm

The volume of the sphere is equal to the volume of the cylinder

Express the Height (H) of the cylinder in terms of y. Write in the simplest form. No idea how to do this. Please show me a method