Question 316751
{{{sqrt(-7)*sqrt(-7)=sqrt(-1*7)*sqrt(-1*7)=sqrt(-1)*sqrt(7)*sqrt(-1)*sqrt(7)=i*sqrt(7)*i*sqrt(7)=i^2*sqrt(7*7)=-1*sqrt(7^2)=-7}}}



Note: {{{i=sqrt(-1)}}} and {{{i^2=-1}}}



So {{{sqrt(-7)*sqrt(-7)=-7}}}


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A Common mistake is this...


{{{sqrt(-7)*sqrt(-7)=sqrt((-7)*(-7))=sqrt(49)=sqrt(7^2)=7}}} which is NOT the correct answer.