(10 Points!) Find the limit by interpreting it as the limit of a Riemann sum of a function

a) limit as n approaches infinity of (1/n)[Sum] from k=1 to n of (k/n)^(1/3)

b) limit as n approaches infinity of (2/n)[Sum] from k=1 to n of (2 + (2k/n))^(-2)

Can someone explain this to me?
!0 Points for best answer!

a) Here, Δx = 1/n. Taking a = 0, we have b = 1, because Δx = (b - a)/n.

Next, a + kΔx = k/n <---> x.
So, f(x) = x^(1/3).

Therefore, this Riemann Sum represents
∫(x = 0 to 1) x^(1/3) dx = (3/4)x^(4/3) {for x = 0 to 1} = 3/4.
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b) This is done similarly.
Here, Δx = 2/n. Taking a = 2, we have b = 4, because Δx = (b - a)/n.

Next, a + kΔx = 2 + 2k/n <---> x.
So, f(x) = x^(-2).

Therefore, this Riemann Sum represents
∫(x = 2 to 4) x^(-2) dx = -x^(-1) {for x = 2 to 4} = 1/4.

I hope this helps!