中考數(shù)學專題復習函數(shù)應用題有答案

ww

,,/:

/.;,,:=

/km

/h

(元/件)與銷售時間

R

R

.

.

.

)

/

/

/

/

yt

/

//

/

/

/

/km /

km km

x

ＡＢＣ

YEA

B

X1.【解析】.

+

+

=

+

+

a=

b

最大值

b

（3）

（3）

)

2.【解析】【答案】（1）

（2）

w

此時，x+200=410，就是說，當每個房間的定價為每天

w

（2）圖中點

（3）由圖象可知，慢車

900km，

/

900km，所以慢車和快車行駛的速度之和為

/

b.

b.

b

，

C

，

b

b，

≤≤（5）慢車與第一列快車相遇

4.5h．

112.5km，所以兩列快車出發(fā)的間隔時間

0.75h．4．解：

2090≤25x+28（80－x）≤2096，48≤x≤50，x

（2）公司獲利潤

W=5x+6（80－x）=480－x，當

（3）W=（5+a）x+?6（80－x）=480+（a－1）x，

5.【解析】【答案】解：（1）政策出臺前的臍橙售價為

（2）設剩余臍橙為

噸,則

=3

10噸；

mn,

mn;m

（3）①設這個一次函數(shù)的解析式為

mx

解得

萬元），則

，

/

過(0，20)、(5,39)、(10,48)三點，解得：a=-0.2，b=4.8，c=20．

+4.8x+20(0≤x≤10)(2)令①式中的

y=36，即-O.2x+4.8x+20=36，=4，x

經(jīng)過點(20，48)、(40，20)，即,解得

36。

解：（）設

b

b

b

b

b

.

···································································

b，

，

b

b. b

·······································

C

m， m，

mx

m.

·

·········································

·

······································································································

····································································

·

··················································································

······································

·

······································································································

=0.代入得

a=，

+6t(0≤t≤40

（2）通過描點,畫圖或分析表二中數(shù)據(jù)可知當

（3）由

11.解：(1)

0≤t

yk

t

點（30，60）在圖象上，∴

60＝30k

k＝2．即

y

t

t

yktb因為點（30，60）和（40，0）在圖象上，

b

b k＝－6，b＝240．

yt＋240．

0≤t

yt

30≤t

y－t＋240．(2)當

0≤t

z