Question

Explain why y=cos^-1x is not a function.

Answer 1

so would that be y= 1/ cos(x) ?

Answer 2

right, but how can prove not function ?

Answer 3

I think it is a function, I don't see how it couldn't be. Sorry I couldn't be of more help.

Answer 4

What set are you using for your domain?

Answer 5

Yes, because there is exactly one output for every input. If you graph this function and draw a vertical line at any point along this function, there is only one intersecting point with this function and the vertical line, which demonstrates this property.