yo im stupid iono wat i was doing wrong... but just to be sure the inverse would be g(x)=sqrt(x^2+16) .... correct? but how would i show that the original is one to one on that interval? ... i mean can i just use f(a)=f(b) and solve, would that show that a=b?

argh but wait when i try to compose the inverse and the original fn both ways...f of g of x and g of f of x, i get -|x|, and then one way it doesnt just give me x, this stuff is confusing the hell out of me, please someone just post up the right answer cuz im goin nuts