Is it? Personally, I think it is since the max power on any unknown is 1, no trig function, no product of unknowns etc. Also could the above mentioned linear equation form a linear system ? I don't think so (cause we always need at least two separate linear equations to form a linear system) but I just want to be sure.(adsbygoogle = window.adsbygoogle || []).push({});

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# Is x1+x2=x3+x4 a linear equation?

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