How do you solve #3w ^ { 3} - 15w ^ { 2} = 42w#?

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Answer 1 · 2017-10-02T07:27:51

There are three solutions:

#w=0" " or w=7" "or w=-2#

#3w^3-15w^2=42w" "larr# set the equation equal to #0#

#3w^3-15w^2-42wcolor(blue)(=0)" "larr# take out a common factor

#color(blue)(3w)(w^2 -5w-14=0)" "larr# factorise the quadratic

#3wcolor(blue)((w-7)(w+2)=0" "larr# set each factor equal to #0#

If #3w = 0" "rarr w=0#

If #w-7 =0" "rarr w =7#

If #w +2=0" "rarr w=-2#