book Maths Puzzle Numerical Ability

Can you please help to answer the following question:
.
Sum the series:
1 x 2 x 3 - 2^3 + 3 x 4 x 5 - 4^3 + ... + 9999 x 10000 x 10001 x - 10000^3

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book Other Question

I'm haveing trouble with radicals. We have a quiz tomarrow and I am not understanding it even with the explanations and examples. I have three samples I hope you could tell me ho 5x^3y+20x^2y^2+20xy^3
all over
5xy

please simplify

note:^ means raised to the power of.