Question 628931
i don't understand how to do a polynomial equation, particularly ones with exponents higher then 2 like x^3+9x^2+23x+15=0
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f(x)=x^3+9x^2+23x+15=0
You can try to factor the expression by grouping, but if this is difficult like given equation, then you must use the rational roots theorem as follows:
Using synthetic division:
...0..|.....1......9.......23.......15
.-1..|.....1.... .8.......15........0 (-1 is a root)
f(x)=(x+1)(x^2+8x+15)=(x+1)(x+5)(x+3)
zeros are: -5,-3, -1
note: you can always check your answer on a graphics calculator like a TI-83+