B\u00e0i 2 (trang 18 SGK \u0110\u1ea1i s\u1ed1 10):<\/strong> X\u00e1c \u0111\u1ecbnh c\u00e1c t\u1eadp h\u1ee3p sau v\u00e0 bi\u1ec3u di\u1ec5n ch\u00fang tr\u00ean tr\u1ee5c s\u1ed1:<\/p>\n\n\n\na) (-12; 3] \u2229 [-1; 4] ; \t \tb) (4; 7) \u2229 (-7; -4)<\/p>\n\n\n\n
c) (2; 3) \u2229 [3; 5)\t;\t\t \td) (-\u221e; 2] \u2229 [-2; +\u221e)<\/p>\n\n\n\n
L\u1eddi gi\u1ea3i:<\/strong><\/ins><\/p>\n\n\n\na) (-12; 3] \u2229 [-1; 4] = [-1; 3]<\/p>\n\n\n\n