The square root of a number means you take that number to the 1/2 power. Our number is c^5. Taking its square root, we have (c^5)^(1/2). When you have exponents like that, you can multiply them together. For example, (x^2)^3 = x^(2*3) = x^6
In this case, we have (c^5)^(1/2) = c^(5*(1/2)) = c^(5/2)