Question 1095268
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Given: x+y=66; xy=9<br>
Find: {{{x^2-y^2}}}<br>
{{{x^2-y^2=(x+y)(x-y)=66(x-y)}}}<br>
{{{(x-y)=sqrt((x-y)^2)=sqrt(x^2-2xy+y^2)=sqrt((x^2+2xy+y^2)-4xy)=sqrt((x+y)^2-4xy)=sqrt(4356-36)=sqrt(4320)=12sqrt(30)}}}<br>
{{{x^2-y^2=(66)(12sqrt(30))=792sqrt(30)}}}<br>