1) The best way to tackle this question is by plotting the graph of this function and then performing the horizontal line test.
So let's sketch out the following function:
Note that this function is a one-to-one function for a horizontal line hits the graph only once.
2) Since, invertible functions can only come from Bijective functions (one-to-one and surjective functions simultaneously) then we can write out this and find the inverse of that inverse function, swapping the variables and then isolating the x on the left side