Date: Jun 20, 2013 7:06 PM Author: Justin Tsui Subject: Want help in linear algebra Can someone tell me why x1+5*x2-sqrt(2*x3)=1 is a linear equation? For I check the definition of a linear equation:"All variables only to the first power and do not appear", and in this case the power of variable x3 is 1/2, not meeting the definition, but why is this equation still be regarded as a linear equation? Thanks.