horizontal compression / stretch

Please explain the following.

The following function is given y=x^3+5x

Write the the equation to represent the following transformation:

1. horizontal stretch as a factor of 2. **y=(1/2 x)^3 + 5(1/2 x)** Is this correct?

2. horizontal compression as a factor of 2? **I do not know**. If a factor is greater than 1, isn't it always horizontal stretch. Shouldn't the factor be less than 1, in order for it to be a compression, like 1/2.

Please explain whether there is a mistake in the assignment, if there is no mistake, please explain how to write the equation.

Thank you.