Question

For what value of c is the function one-to one?

{(1,2),(2,3)(3,5),(4,7),(5,11)(6,c)}

Answer 1

One to one function passes horizontal line test. If you plot function, it would looks like it increasing.

at x=5, you have y=11
so at x=6, y should be greater than 11, right?

Answer 2

without the use of plot or any test
x's and y's
if you see two different values of y's for the same x, then that is not one-to-one. it is possible, however, that you get one value of y different values of x.

Answer 3

choose a y value that has not been used.