Question 189976
factor the pollynomial completely
x3+5x2-8x-40
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In a classroom, these are always integers.
Look at the 40 - a zero will be a factor of 40.
Try (+ and minus) 1, 2, 4 and 5.  f(-5) = 0, so (x+5) is a factor.
Once you divide by (x+5), it's only a 2nd order, easy to factor further, if possible.
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Another approach is to graph the function and look for zeroes.
dl the free software at 

www.padowan.dk.com/graph/