（全國版）2020年中考數(shù)學(xué)復(fù)習(xí) 提分專練01 實(shí)數(shù)混合運(yùn)算與代數(shù)式的化簡求值

提分專練(一)實(shí)數(shù)混合運(yùn)算與代數(shù)式的化簡求值|類型1|實(shí)數(shù)的運(yùn)算1.2018·陜西 計(jì)算:(-3)×(-6)+|2-1|+(5-2)0.2.2019·南充計(jì)算:(1-)0+|2-3|-12+12-1.3.2019·廣安計(jì)算:(-1)4-|1-3|+6tan30°-(3-27)0.4.2019·遂寧計(jì)算:(-1)2019+(-2)-2+(3.14-)0-4cos30°+|2-12|.|類型2|整式的化簡求值5.2019·常州如果a-b-2=0,那么代數(shù)式1+2a-2b的值是. 6.2019·常德若x2+x=1,則3x4+3x3+3x+1的值為. 7.2019·淮安計(jì)算:ab(3a-2b)+2ab2.8.2019·吉林 先化簡,再求值:(a-1)2+a(a+2),其中a=2.9.若x+y=3,且(x+3)(y+3)=20.(1)求xy的值;(2)求x2+3xy+y2的值.|類型3|分式的化簡求值10.2019·淮安先化簡,再求值:a2-4a÷1-2a,其中a=5.11.2019·黃石先化簡,再求值:3x+2+x-2÷x2-2x+1x+2,其中|x|=2.12.2019·菏澤先化簡,再求值:1x-y·2yx+y-1÷1y2-x2,其中x=y+2019.13.2019·天水先化簡,再求值:xx2+x-1÷x2-1x2+2x+1,其中x的值從不等式組-x1,2x-1<5的整數(shù)解中選取.14.2019·荊門先化簡,再求值:a+ba-b2·2a-2b3a+3b-4a2a2-b2÷3ab,其中a=3,b=2.15.2019·遂寧先化簡,再求值:a2-2ab+b2a2-b2÷a2-aba-2a+b,其中a,b滿足(a-2)2+b+1=0.【參考答案】1.解:(-3)×(-6)+|2-1|+(5-2)0=18+2-1+1=32+2=42.2.解:原式=1+3-2-23+2=1-3.3.解:原式=1-(3-1)+6×33-1=1-3+1+23-1=1+3.4.解:(-1)2019+(-2)-2+(3.14-)0-4cos30°+|2-12|=-1+14+1-4×32+23-2=-74.5.56.4解析3x4+3x3+3x+1=3x2(x2+x)+3x+1=3x2+3x+1=3(x2+x)+1=4.7.解:ab(3a-2b)+2ab2=3a2b-2ab2+2ab2=3a2b.8.解:原式=a2-2a+1+a2+2a=2a2+1,當(dāng)a=2時(shí),原式=2×(2)2+1=2×2+1=5.9.解:(1)(x+3)(y+3)=20,xy+3x+3y+9=20,即xy+3(x+y)=11.將x+y=3代入得xy+9=11,xy=2.(2)當(dāng)xy=2,x+y=3時(shí),原式=(x+y)2+xy=32+2=9+2=11.10.解:a2-4a÷1-2a=a2-4a÷a-2a=a2-4a·aa-2=(a+2)(a-2)a·aa-2=a+2.當(dāng)a=5時(shí),原式=5+2=7.11.解:原式=x2-1x+2÷(x-1)2x+2=(x+1)(x-1)x+2·x+2(x-1)2=x+1x-1.|x|=2,x=±2,由分式有意義的條件可知:x=2,原式=3.12.解:1x-y·2yx+y-1÷1y2-x2=1x-y·2y-(x+y)x+y·(y+x)(y-x)=-(2y-x-y)=x-y.x=y+2019,原式=y+2019-y=2019.13.解:原式=x-x2-xx(x+1)·x+1x-1=-xx+1·x+1x-1=x1-x.解不等式組-x1,2x-1<5得-1x<3,則不等式組的整數(shù)解為-1,0,1,2.x±1,x0,x=2,原式=21-2=-2.14.解:原式=2(a+b)3(a-b)-4ab3(a+b)(a-b)=2(a+b)2-4ab3(a+b)(a-b)=2(a2+b2)3(a+b)(a-b).當(dāng)a=3,b=2時(shí),原式=2(3+2)3(3+2)(3-2)=103.15.解:原式=(a-b)2(a+b)(a-b)÷a(a-b)a-2a+b=a-ba+b·1a-b-2a+b=-1a+b.(a-2)2+b+1=0,a=2,b=-1,原式=-1.6