You are told that the y is proportional to x^2 and that when y=75, x=5. Find a formula for x in terms of y.

If we know that y is proportional to x² then we using the given values we can write 75= 5² --> 75=25, however this is obviously not true but all that remains is to multiply the 5² by 3 which gives us 75=3(5²) --> 75=75