ĐỀ 62 = − + +y x x C!"# $# C%&'()m*&!"#+,-*./ 0− + − =x x m 1+,-*./ + + + = x x 233!+ 0 4! 5 π = + ∫ I x x x 2/*. '67%*. 87!"# 9+ = x y x . : ; <= 2.*>?**#!#*! SOM ?*@ O% · 0=MSO % =OM A#B,C**7+>D! SOM E#.F!SO@.#/G 235&3!H*E#!"#/G 233!>G < 2.*>?**#Oxyz%! ; ; −A % ; ; <B I 0 α + − + =x y z J+,-*./K!LS(AB',C*>3 J+,-*./K+M* β E#A*C?**G!6#K+M* α Oxy 4 2/?!"#+N! = − − +z i i . ĐỀ 62 = − + +y x x C!"# $#