ĐỀ THI THỬ ĐẠI HỌC NĂM HỌC 2012-2013 MÔN TOÁN ĐỀ 2 ppt

Nguoithay.vn sinh- I f ( x) g ( x) f ( x) f ( x) g ( x) g ( x) f ( x) g ( x) g ( x) g ( x) f ( x) g ( x) f ( x) g ( x) g ( x) f ( x) g ( x) f ( x) g ( x) g ( x) g ( x) 0 f ( x) nh g ( x) I Nguoithay.vn Nguoithay.vn x x (1) x x x Do x2 (1) x x x x x2 x2 x x x2 x 4 x2 x x4 x 1 (2) 4 x2 x x4 4 x2 x4 x 0 1-x x 1 x x (1) x x x2 x2 x2 x x2 4 x2 x4 x : ( x 3) x x2 (1) (1) ( x 3)( x2 x2 x2 x x2 -4 |x| x 3) (2) x x 13 x2 x x x 13 x -2 13/ + x2 6x - + -13/6 x x 10 x2 x2 (1) -x2 10 x2 Nguoithay.vn Nguoithay.vn x x 10 x2 10 x 10 x2 x( x x2 6) x x 12 x x 0, x 11x x2 18 6 36 x 0, x 3, x x x 2 + x2 x 0, x 9, x x x 10 x2 0 (2) x (10 x ) x2 + 10 10 10 x ,3 x 10 : x t= x t2 t x , x t2 x 1 2t x x2 x x2 x (1) x x x x 2x x x x t2 t=1,t=- x x x2 x x 1 nên t x x x( x 1) t2 x x x x2 x x x Nguoithay.vn Nguoithay.vn 3x x2 7x 3x 2 x2 5x (1) 3x 3x 7x x2 20 3x 5x x2 3x x 3x x 7x 2 3x 3x2 x2 3x x a b 3x 3x c a2 b2 5x c 3x c ) 2(d 3(a a , b, c 0, d a c 2 3(a c2 ) 2(d b2 ) d2 c d (1) a d 7x 2 b ) x 3x x2 a b c d (a c)(3a 3c 2b 2d ) a , b, c 0, d 5x x 4x 28 7x t 4x 28 -1/2) x2 (1) 7t 2 x 7x t 7t t2 (1) t 14 x x 7t (3) x t x 7t x-t=0 t=x Thay vào (2) ta có 7x2+7x= x x 7t (2) 7(x2-t2)+7(x-t)=t-x (x-t)(7x-7t+8)=0 i 4x 4x 28 b 5x 3x (*) nên x 2 14x2+12x-1=0 14 Nguoithay.vn Nguoithay.vn ii 7x2+7x+8=0 t ta có x t 7x 7 23 , x 14 2(1 x) x2 x2 , 23 x 7x , thay vào (2) ta có : 23 x +7t+8=0 2x t2 x2 2 x x2 x (1) x2 x (*) 2x 2(1-x)t=t -2x+1-2x-1 hay t -2(1-x)t2 t=(1-x) +4x=(1+x) t1=1-x+1+x=2, t2=1-x-1- x=2x i +2x-1=22=4 x2+2x-5=0 x ii x2 2x 2x 2x x2 x x x2 x x3 (1) x x2 u 0, v x 2( x2 2) u x 1, v2 u x2 2( x2 3x 2x 2) (1) x3 x -1 x 1, v x2 x x u v2 x2 Thay vào +v2), suy 2u2-5uv+2v2 1=2v, u2 = v i 4x ii 5x v x x x2 x 52 4.4.3 x x 4( x 1) x 4( x2 ( x2 x 1) , x 1) Còn Nguoithay.vn Nguoithay.vn : x x (1) x x x x 4( x 1) ( x 2) x 4( x 1) x x x ( x 1)( x 2) 11 x x (2) 0, (3) x2 x 11 x 11 15 x 126 x 153 16( x 2 x x ta có : x 2) 3( x 2)(2 x x 3) ( x 2)(2 x x x x x 2) 121 110 x 25 x 11 15 x 14 x 17 11 15 x x x + + 2 x2 x2 x2 3x x2 2x x (1) x 2 x2 x2 3x x2 2x x2 3x x2 (1) x2 x 2 x2 2x x2 x x2 2x 2( x 2) x 2x x2 2x (*) x2 3x x2 3x ( x x x2 3x x x x 2) 2 2x 2x x x 2x x 3x x2 x Nguoithay.vn Nguoithay.vn -2 : mx m (1) x x có: (1) m( x 1) x x (do x nên x-1 0) x m x x y x Ta Ta có: x y' y' y' x x x x ( x 1) 2 x 14 x 37 Lim y x x x x Lim x x x x x x x x ( x 1) x x x x x 2( x 3) x 4( x 3) x 3 + + - y m m 25 10 x x m x2 x x2 y x x m (1) x x2 x R Ta có: Nguoithay.vn Nguoithay.vn 2x y' x 2x x (2 x 1) x x x (2 x 1)(2 x 1) (4 x x x Lim y x x x (2 x 1) x 2 2x x2 x x x (4 x x 1) x 1)( x x 1) x2 Lim x x2 x x 1 x x2 Lim x x2 1 x x2 x 1 x x x x2 x x2 x x2 x x 1 x2 1 x x2 x 2x Lim x2 x Lim 2x Lim x x 2x y' 0 x 1)( x Lim Lim y x 1 x2 - + + +1 y -1 -1