How do you find the zeros of #f(x) = x^3 – 9x^2 + 20x#?

1 Answer
Apr 5, 2016

Answer:

Factor then recognizing that one of the terms must be equal to zero for the zero of the function:
#color(white)("XX") x=0 or x=4 or x=5#

Explanation:

#x^3-9x^2+20x#
#color(white)("XXX") =x(x^2-9x+20)#

#color(white)("XXX") =x(x-4)(x-5)#

If #f(x)=x^3-9x+20x=0# then
#{("either ",x = 0,),("or",(x-4)=0,rarrx=4),("or",(x-5)=0,rarr x=5):}#