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Hello,

I need help to explain about the problem 1.27, I don't know how to factor it, please advise, thank you!

This is for Math Challenge II-B Algebra, correct? Please remember to let us know from which course you need help.

Try adding and subtracting $ab$: $$a^3b - ab^3 + a^2 + b^2 + 1 = a^3b - ab^3 + a^2 -ab + b^2 + ab + 1$$

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