Four positive numbers, each less than 50, are rounded to the first decimal place and then multiplied together. Use differentials to estimate the maximum possible error in the computed product that might result from the rounding. I took f(w,x,y,z) = wxzy and then you set df=xzy(dw)+wzy(dx) etc and you will eventually wind up with 4(50)^3(___) as the possible error. I'm having trouble filling in the blank. I'm not sure what dw, dx, dy, and dz would be. Any help?