【導(dǎo)讀】7.-18.69.y=x2-3x+210.直線x=311.a(chǎn)>94?且a≠012.向上13.-8. 19.y=x2-2x-3;略20.222283539999yxxx??????兩個(gè)交點(diǎn);交于負(fù)半軸;當(dāng)x<13時(shí),y隨x的增大而減小等22.任意實(shí)數(shù);坐標(biāo),對(duì)稱軸是直線x=1;當(dāng)x<-1或x>4時(shí)y>0:當(dāng)x=-1或x=4時(shí)y=0:。元26.y=-x2+4x-2;y=-x2+12x-3227.10;S=55;描點(diǎn)(略);經(jīng)觀察所描各點(diǎn),它們?cè)谝粭l拋物線上.S=12n2+12n28.y=2901x?12.x<-2或x>813.y=15x2-85x+3等14.圖象都是曲線,都過點(diǎn);圖象形狀。值先到達(dá)16;如:y3=(x-4)2+1625.略;2726.100(8-x)(件);900-100x(件);y=(x-6),即y=-100x2+1500x-5400;x=元時(shí),1.152cm,92cm2.453.,4.1:45.、(3,3)、6.∠ACP. =∠B或∠APC=∠ACB或ABAPAC??27.4條8.3,59.2種10.611.AC,19.20.略21.略22.能,有三個(gè),AP=或214115?23.△ABC∽△ADE,7.-28.49.40>210.1211.y=-(x-1)212.4513.20201()2. ;70元,9000元26.6m27.。x;能夠通過此隧道28.略;1963272yxx?????△EFD6.;,(2,0)7.±128.4條9.3,510.611.y=x2-2x. 21.直角三角形22.∠A=30°或∠A=60°23.BF==CE,DE=13,CF=BE=,