∂x∂f=3x+2y−1 ∂y∂f=2x+6y+4 Egs=2α+8α1 ∂α∂E=21−8α21 EGS=2α+8α1+2β+8β1 ∂α∂E=21−8α21 ∂β∂E=21−8β21