Adding and subtracting proof
can not come up with one
start with the formula: dependent equals constant times independenty=x+z{\displaystyle y=x+z} then δy=(δx∂(x+z)∂x)2+(δz∂(x+z)∂z)2=δx2+δz2{\displaystyle \delta _{y}={\sqrt {\left(\delta _{x}{\frac {\partial {\left(x+z\right)}}{\partial x}}\right)^{2}+\left(\delta _{z}{\frac {\partial (x+z)}{\partial z}}\right)^{2}}}={\sqrt {\delta _{x}^{2}+\delta _{z}^{2}}}}