求證明極限lim(x,y)->(0,0)(x^2 * sin^2y)/x^2 +9y^2 =0 如題,求證明該極限=0

求證明極限lim(x,y)->(0,0)(x^2 * sin^2y)/x^2 +9y^2 =0 如題,求證明該極限=0

x^2/(x^2+9y^2)0
所以由夾逼法則,
lim(x,y)->(0,0)(x^2 * sin^2y)/(x^2 +9y^2)=0