Well, you found a counter-example, then it cannot be true.
What if ?
I am working on this problem it makes sense to me but there is something inside screaming that it is wrong... here it is.
Consider the equation x^4y+ay+x=0
a) Show that the following statement is false. "For all a,x, in real Numbers, there is a unique y such that x^4y+ay+x=0.
basically i solved for y getting y= -x/(x^4+a). Then explained it as it must be false because x and a are variables spanning R and are conditional to each other so it must be false.
b was just proving that it was true when the equation had to work for x in all real's
Help?? or validate.
There will be many more than just a "single value" for y; the set of y-values should be uncountably infinite.
Hope that makes it somewhat clearer to you.