1. The difference is wX + W2X2-y. The squared difference is L= (W1X1+W2X2 - y)(W1X1+W2X2-y). Multiply this out L = W1X1 (W1X1+W2X2 y) + WX1 (W1X1 + W2X2 y) y(W1X1 + W2X2 - y) = Wx+ WX1W2X2 - WXY + ... and combine identical terms into L = wx+ 2W1X1W2X2-2W1X1Y + ... 2. Now compute the partial derivatives BL/DW1= and al/aw= 3. Show that (fill out the missing factors) al/aw1= (W1X1+WX-y) and L/Ow= (Wx1+ W2x2 - y). What w = (W1, W2)T makes the gradient (OL/Ow, DL/dw) = 0? (Solve the normal equation?)