(a) Let f:RR be a function defined by f(x)=x2+1x,xR Is f one-to-one? (b) If f:XY and g:YZ are functions and gf is one-to-one, must g be one-toone? Jostify your answer. (c) For all C,DY and any function f:XY, determine whether the following is true: f1[CD]=f1[C]f1[D].