The length of a side of square S1 is x, and the length of a side of square S2 is five times larger then the area as square S1, what is y in terms of x ?

please answer and explain

assuming y is the side of S2, then working with what you have written,

S1 = x^2
y = 5x^2

However, assuming you meant the area of S2 is 5x the area of S1, then y=sqrt(5)*