1、 2018 11 :( 10 3 30 1 2 x x 2 +mx+1=0 m A 0 B 1 C 2 D 3 2 1 2 1 2=6 1 2 1 2=6 4 x (x 1) 2 1 k k A k 1 B k 1 C k 1 D k 1 5 22 22 y x x m = - + + (m ) ( ) A. B. C. D. 7 4cm 9cm . A.2.5cm 6.5 cm B.2.5cm C.6.5cm D.5cm 13cm 8 5 O AB CD P AB=CD=8 OP A 3 B 4 C 3 2 D 4 2 9 2 1 1 n n n 2 n 210 x AB 1 C 2 x y
2、 x 0 2 C 4 2 x y x 0 A B A CD x y C2 C D B A B C D EF x y C1 E F EAD OBF S S A 6 2B 4 2C 4 1D 6 1 :( 6 3 18 11 1 1 x x 2 2 3 0 ax x a 2 , 2 3 4 0 xx 2 3 a 3 O 6cm O AB 6 3 AB 4 A 1 5 B 3 3 C 5 3 D 3 1 AB CD 5 AC=BC= 2 A = . 6 1 9 A r A 3 r 72 12 ( 4 8 1 2x 2 x=1 2 x 2 +4x+2=0 A B A C C B 5 4 6 13 7
3、x x 2 2x k 1 0 (1) k (2) k 1 x 2 2x k 1 0 k 14 7 AB O CD AB E ACD=30 AE=2cm D B 16 8 O 1 A P B C O . APC= CPB=60 . (1) PA PB PC (2) P APBC . 17 8 ABCD MNPQ AN AM CP CQ x m BC 200 m AB a m a 200 MNPQ S m 2 (1) S x x (2) a 400 S x (3) a 800 S 18 8 1 Rt ABC 90 A AB AC D E AB AC A B C P O AD AE DC M P N
4、 DE DC BC . 1 1 PM PN 2 ADE A 2 MN BD CE PMN 3 ADE A 4 AD 10 AB PMN . 19 9 x x 2 + k 5 x+1 k=0 k . 1 k 2 y=x 2 + k 5 x+1 k 3 3 3 k . 20 10 xOy c bx ax y 2 ) 2 3 , 0 ( A . 1 ) 2 1 , 2 ( B x F E, . b a EF EF 2 2 1 a 1 0 x x 3 b . CDBDA CACDD 1 -1 2 0 3 60 120 4 1 1 4 4 5 1 3 6 2 3 17 r 1 ) 1 ( 1 x , 2
5、 1 2 x (2) 2 2 , 2 2 2 1 x x -2 3 4 2 3 . ) 200 0 ( ) 200 ( 2 2 x x a x S (2) 45000 ) 150 ( 2 2 x S 120000 PM=PN, PMN PMN 2 49 19 1 3 = k 5 2 4 1 k =k 2 6k+21= k 3 2 +12 0 k 2 3 y=x 2 + k 5 x+1 k a=1 = k 3 2 +12 0 x x x1 x2 x1+x2=5 k 0 x1 x2=1 k 0 k 1 k k 1 A B C P O D 3 3 x1 x2 x1 3 x2 3 0 x1 x2 3
6、x1+x2 +9 0 x1+x2=5 k x1 x2=1 k 1 k 3 5 k +9 0 k 2 5 k 2 -2a-1 3 y=ax 2 2a+1 x+ 3 2 y=0 ax 2 2a+1 x+ 3 2 =0 = 2a+1 2 4a 3 2 =4a 2 2a+1=4 a 1 4 2 + 3 4 0 x1 x2 x1+x2= 21 a a x1x2= 3 2a EF 2 = x1 x2 2 = x1+x2 2 4x1x2= 2 2 2 4 2 1 1 13 aa aa a=1 EF 2 EF 3 y=x 2 3x+ 3 2 2 4 a= 1 2 y= 1 2 x 2 +bx+ 3 2 x= b x=0 x=1 x= b x x=0 y= 3 2 x=1 y= 1 2 +b+ 3 2 =2+b x= b y= 1 2 b 2 +b b + 3 2 = 1 2 b 2 + 3 2 |2+b|=3 b=1 b= 5 0 x 1 | 1 2 b 2 + 3 2 |=3 b= 3 x= 3 0 x 1 b 1 5
