1. The problem statement, all variables and given/known data If z=x^2-xy+3y^2 and (x,y) changes from (3,-1) to (2.96,-.95) compare the values of Δz and dz. 3. The attempt at a solution So I plugged the two given sets of (x,y) into and solved for z and subtracted one from the other and got |.7189|. I don't know what the question means when it says compare it to dz. Since z is a function of two variables how do I do this? To I take the partial with regards to each variable or whaaat? does anyone know what the question is asking?