Question 559335
{{{y=3.5+5x+0.5(-1)^x}}} would work for integer values of x
{{{y=3.5+5x+0.5cos(pi*x)}}} would work too
I suspect that the expected solution is simpler than I'm making it, too.
Otherwise, could it be that the missing steps were expected to be different from what you filled?
The person who wrote that problem probably think there could be only one solution.