Question 976975
What are the rational zeros of this function? Please explain each step. 
f(x) = x^3 – 21x – 20 
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use rational roots theorem with synthetic division:

...0...|.....1......0......-21.......-20.......
.-1...|.....1.....-1......-20........0. (-1 is a zero)
f(x)=(x+1)(x^2-x-20)
f(x)=(x+1)(x+4)(x-5)
rational zeros are: -1, -4, and 5