Very difficult Real Analysis question on Lebesgue integration

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Suppose gn are nonnegative and integrable on [0, 1], and that gn \rightarrow g almost everywhere.

Further suppose that for all \epsilon > 0, \exists \delta > 0 such that for all A \subset [0, 1], we have

meas(A) < \delta implies that supn \intA |gn| < \epsilon.

Prove that g is integrable, and that \int[0,1] g = lim \int[0,1] gn.

Attempt at the solution:
There are some observations I've compiled. First, for an set A with measure less than \delta, we know that the the limiting function g exists on that set. So, it's integral is also bounded by the sup. But from here, I don't know how to argue that the limiting function has a uniform bound on all of [0, 1].
 
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Have you tried any of the well-known theorems in Lebesgue integration regarding interchange of limit and integral?
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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