9 and 18

For number nine, i wrote that the statement is true. If there is a linear function, it is in the form of y=mx+b. To find the inverse, simply replace x and y with each other to get x=my+b. Solve for y and you get y=(x-b)/m which is still a linear equation.

For number 18, this is what i did:
logx=a logy=b
log(10sqrt(x)/y^2) can be rewritten as log10+log(sqrt(x))-logy^2 which can be rewritten as
1+.5*logx-2logy
which is 1+.5a-2y