Baứi 1 (3im) a) Khi lng ca 40 tỳi ng c úng gúi bi t A ( n v: kg) Lp khi lng (kg) Tn sut(%) [1,90; 1,98) [1,98 ; 2,06) [2,06 ; 2,14) [2,14 ; 2,22) [2,22 ; 2,30] 42,5 42,5 7,5 5,0 2,5 Cng 100(%) 1,5 1 b) Khi lng ca cỏc tỳi ng di 2,14 Kg chim 92,5(%). 1,94.17 + 2, 02.17 + 2,1.3 + 2,18.2 + 2, 26.1 2 ( kg ) 40 a) 7x2 x + 6 > 0 x = 1 2 7 x x + 6 = 0 x = 6 7 x - -1 6/7 + VT - 0 + 0 6 Võaọy taọp nghieọm:T= 1; ữ 7 2 2 x + 3x + 1 0 b) x2 2x + 3 x =1 x2 2 x + 3 = 0 x = 3 0,5 x = 1 2 x 2 + 3x + 1 = 0 x = 1 2 Lp bng xột du: - -3 -1 x 2 0 + x 2x + 3 2 + + 0 2 x + 3x + 1 VT + 0 Vy tp nghim T = (-3;-1]U[-1/2;1) 0.5 c) x = Baứi 2 (3im) Baứi3 (4im) -1/2 + 0.5 0.5 1 + 0 0 0.5 0 + + + 0.5 + 0.5 uu ur a) VTCP AB = ( 6;8 ) . 0.5 PT tham soỏ cuỷa AB: x = 6 + 6t y = 30 + 8t 0.5 uu ur r b)VTCP AC = ( 24;6 ) n = ( 1; 4 ) 0.5 PTTQ ca ng thng cha cnh AC : x + 4y + 114 = 0. 1 c) Gi I l trung im ca BC ta cú I ( 3; 23) 0.5 Bỏn kớnh R = BI = 152 + 12 = 226 Phng trỡnh ng trũn (C) ng kớnh BC l: ( x + 3) + ( y + 23) = 226 . 2 2 0.5 0.5