4. Consider the function f : R2 } R dened by my if my 3 I], H35, 9) Z {32 if my :f U. I+y2 (a) Show that f is continuous on {(m,y) E R2 : m = D} (i.e. everywhere on the yexis). Hint: Given ya E R, show that |f{m,y}| E [1 + |y.}|)|m| for all [m,y) E D1{(, {10)} (b) Show that f is not continuous on {(m,y) E ]R2 : m 35 I], y : [1} (Le. everywhere on the mexis except at the origin)