Question 113714
{{{x^2-9x =-20}}} Start with the given equation



{{{x^2-9x+20=0}}} Add 20 to both sides




{{{(x-5)(x-4)=0}}} Factor the left side (note: if you need help with factoring, check out this <a href=http://www.algebra.com/algebra/homework/playground/change-this-name4450.solver>solver</a>)




Now set each factor equal to zero:


{{{x-5=0}}} or {{{x-4=0}}}


{{{x=5}}} or {{{x=4}}}  Now solve for x in each case



So our solutions are {{{x=5}}} or {{{x=4}}}



Notice if we graph {{{y=x^2-9x+20}}} we get


{{{ graph(500,500,-10,10,-10,10, x^2-9x+20) }}}


and we can see that the graph has roots at {{{x=5}}} and {{{x=4}}}, so this verifies our answer.