1、 2018 ( 3 , 45 ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 D D D C B C B C B D A C C C C ( 3 , 18 ) 16. x1=0,x2=-1 17. 2 518.8 19.22.5 20. 3 21. 1 3 n 22.(8 )(1)x1=1,x2=3 4 (2)x1=3,x2= 2 3 4 23.(8 ) 1 P 2 = 4 1. 3 2 6 12 5 4 P 5 = . 8 24.(6 ) AB=2 DB= AB DB=1 BD AB AD2=AB2+DB2 AD= 5 AC=AE= 5 -1 2 1 5 AB A
2、C C AB 6 25. (8 ) 1 ABDE AB=DE AB=AC DE=AC AB=AC D BC ADC=90 D BC CD=BD CD AE CD=AE AECD ADC=90 ADCE -4 41 12 3 2 ADCE AO=EO AOE=60 AOE AO=4 AC=8 -8 26.(9 ) 1 ABCD B= C=90 PE AP APB+ CPE=90 CPE+ CEP=90 APB= CEP ABP PCE-4 2 P BC E CD , BC=m,CD=4 BP=CP= m 2 1 ,CE=2 ABP PCE CE BP PC AB 2 2 1 2 1 4 m m
3、m= 2 4 . m 2 4 -9 27.(9 )(1)80 x 200 10x 400-10x -3 (2) 80 200 (80 x)(200 10x) 40(400-10x) 50 800 9 000 x 2 20x 100 0. x1 x2 10. x 10 80 x 7050. 70 -9 28.(9 )(1) ABCD AB AD. m 2 4( m 2 1 4 ) m 2 2m 1 (m 1) 2 (m 1) 2 0 m 1 ABCD m 1 x 2 mx m 2 1 4 0 x 2 x 1 4 0. x1 x2 1 2 . ABCD 1 2 .-4 (2) AB 2 x 2 mx m 2 1 4 0 4 2m m 2 1 4 0. m 5 2 . m 5 2 x 2 mx m 2 1 4 0 x 2 5 2 x 1 0. x1 2 x2 1 2 . AD 1 2 . ABCD ABCD 2(2 1 2 ) 5.-9
