Evaluate the following integrals as a limit of sums:

Formula used:

where,

Here, a = 0 and b = 3

Therefore,

⇒ nh = 3

Let,

Here, f(x) = x + 4 and a = 0

Now, By putting x = 0 in f(x) we get,

f(0) = 0 + 4 = 4

Similarly, f(h) = h + 4

In this series, 4 is getting added n times

Now take h common in remaining series

Put,

Since,