Question 186435
{{{u^2=4u}}}  Start with the given equation



{{{u^2-4u=0}}} Subtract 4u from both sides.



{{{u(u-4)=0}}} Factor out the GCF "u"



Now set each factor equal to zero (using the zero product property):


{{{u=0}}} or  {{{u-4=0}}} 



{{{u=0}}} or  {{{u=4}}}    Solve for "u" in each case



So the solutions are 


 {{{u=0}}} or  {{{u=4}}} 



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Check:


Let's check {{{u=0}}}


{{{u^2=4u}}}


{{{0^2=4(0)}}}


{{{0=0}}} works


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Let's check {{{u=4}}}


{{{u^2=4u}}}


{{{4^2=4(4)}}}


{{{16=16}}} works