The definition of a definite integral in terms of sum and limits is given by:
∫ba f(x) dx = limn→∞ ∑ni=1 f(xi) Δx
Where Δx = (b-a)/n
xi = a + Δx• i
The given limit is:
limn→∞ ∑ni=1[ 5(xi)3 - 5xi ] Δx , [2,4]
That means:
f(xi) = 5(xi)3 - 5xi
f(x) = 5x3 - 5x
Therefore our definite integral is:
∫42 (5x3 - 5x) dx