... i x i= Thỡcỏcshng cha x cúckhi i ẻ{23 Vy hsphitỡml } 4 C10 + C10 36 + C10.16 =80 85. NHểMHCSINHLP12A1 TRNGPTDTNITRTHI NGUYấN ... ngthngtho gi thit. VyPT ca 2ngthngtỡm c l x - y - 23 = x + y - 15 =0 www.VNMATH.com 2)TotipimHl giaoimcamtphng ( a) quaAvvuụnggúcvi D ,tớnhcPT ( a) l x - y + z + 12 =0,t úcúc ổ 1 28 212 116ử Hỗ ... nờncúPT x - 16 y - 13 z + 31 =0. CõuVIIa n ( W )=C20.tA: "Chn 3ngitrong úcú 1cplvchng"thỡ n ( A )=4. 18. ( ) 72 C 20 Vy xỏcsutcn tỡm P A = - P ( A = 1- ) CõuVIb.1)PT ng D cú dng uu uu r r y = k ( x...