Question

which function is one to one f(x)=abs(x), f(x)=2^x, f(x)=x^2 or f(x)=sinx

Answer 1

one to one function means for every y value there is only one x value. If you see that Abs fuction is v shaped. so you have 2-x values for one y. X^2 is a quadratic fn. with parabola curve. also has 2 x values for one y. Sin function has sinusoidal wave. has many x values for one y. So y = 2^x is the only function that is one to one.