Kiem tra so 6 chuong III

Trờng THCS Trực Định
Họ và tên : ...............................................
Lớp : ..........................
Bài kiểm tra 1 tiết
Môn: Số học
Thời gian 45 phút
Phần I: Trắc nghiệm khách quan (3 điểm)
Em hãy khoanh tròn vào chữ cái đứng trớc phơng án mà em cho là đúng.
Cõu 1: Bit rng
22
11 121

=

, hi s thớch hp in vo v trớ l s no?
A. 2 B. 2 C. 11 D. 11
Cõu 2: Khi quy ng mu cỏc phõn s
3 11 7
; ;
20 30 15
thỡ mu s chung l s no?
A. 30 B. 30 C. 60 D. 90
Cõu 3: Kt qu ca phộp tớnh
3
2
3


ữ

bng bao nhiờu?

A.
8
27
B.
8
27

C.
6
9
D.
6
9

Cõu 4 : Trong cỏc phõn s sau, phõn s no ln hn
2
3

nhng nh hn
1
2

?
A.
5
12

B.
6
12

D.
7
12

D.
8
12

Cõu 5 : S nghch o ca
2
5
3

l :
A.
2
5
3
B.
3
5
2

C.
17
3

D.
3

17

Cõu 6 : Cho a Z , tỡm a bit
8 1 -2 5
a
3 3 7 7

+ < < +
ta c:
A. a = 2 B. a = 3 C. a = -2 D. a = - 3
Phần II: Tự luận (7 điểm)
Bài 1 : Thực hiện phép tính :
a, 2
2
1
+ (
3
2

ì
6
4


4
9
) b,
21
12

ì
7
2
+
7
12
ì
4
)3(

Bài 2: Tỡm x, bit:
a)
4 2 1
7 3 5
xì =
b)
7 4
15 7
+
1
:
5
x

=
Bài 3: Ba vòi nớc cùng chảy vào một cái bể cha có nớc. Nếu chảy riêng thì vòi thứ nhất chảy trong 3 giờ
đầy bể, vòi thứ hai trong 4 giờ đầy bể, vòi thứ ba trong 6 giờ đầy bể.
a) Trong một giờ, mỗi vòi chảy đợc bao nhiêu phần của bể?
b) Trong một giờ, cả ba vòi chảy đợc bao nhiêu phần của bể?
c) Nếu cả ba vòi cùng chảy thì sau bao lâu sẽ đầy bể?

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