7-8 Show that the limit does not exist by considering the limits as (x, y)(0, 0) along the coordinate axes. 3 (x,y)(0,0) x2+2y2 yx+y 7. (a) lim (b) lim (x,y)(0,0) 2x2 + y² x-y 8. (a) lim cos xy (b) lim (x,y)(0,0) x2 + y² (x,y)(0,0) x²+y2