KT Dai8 Chuong I

Trường THCS Hồ Thị Hương
Lớp : …………. MS : ……………
Họ và tên HS: …….....................………………

............., ngày …….tháng ……năm 2009
TRA CHƯƠNG I
Môn : ĐẠI SỐ 8.
Thời gian làm bài : 45 phút (Không kể thời gian giao đề)


Điểm:
Lời phê của giáo viên :









ĐỀ 1 :
I/. TRẮC NGHIỆM: (2 điểm)
Điền dấu “X” vào ô thích hợp:

Câu
Nội dung
Đúng
Sai

1
( x – 1)2 = 1 – 2x + x2



2
x3 + 8 = (x + 2) ( x2 – 4x + 4)



3
– 4x (x + 4) = – 4x2 + 16x



4
232 – 46.18 +182 = 25



5
( 25x2 – 9y2 ) : (5x – 3y) = 5x + 3y



6
16 – x2 tại x = 6 có giá trị là 20



7
(x – 2)3 = x3 – 6x2 + 12x – 8



8
(x – 2)2 = x2 – 4




II/. TỰ LUẬN: (8 điểm)
Bài 1 : ( 3 đ) Phân tích các đa thức sau thành nhân tử :
x2 – y2 – 7x + 7y = .........................................................................................................................
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9 – x2 + 2xy – y2 =............................................................................................................................
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c) x2 – 5x + 6 = .........................................................................................................................
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Bài 2 : ( 2 đ) Rút gọn các biểu thức sau :
(x + 3)2 – 2(x + 3)(x – 2) + (x – 2)2 =
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(x + 2)2 – (x – 4)(x + 4) =
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Bài 3: ( 2 đ)Tìm x, biết:
x3 – 25x = 0.
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x(x – 3) – 4x + 12 = 0.
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Bài 4: ( 1đ) Tìm a để đa thức 3x3 + 2x2 – 7x + a chia hết cho đa thức 3x – 1

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ĐÁP ÁN ĐẠI 8 - C I
ĐỀ 1 :
I/. TRẮC NGHIỆM: (2 điểm)
Mỗi câu trả lời đúng: 0.25 đ
Câu
1
2
3
4
5
6
7
8

Đáp án
Đ
S
S
Đ
Đ
S
Đ
S


II/. TỰ LUẬN: (8 điểm)
Bài 1 : ( 3 đ) Phân tích các đa thức sau thành nhân tử :
(Mỗi câu đúng: 1 điểm)
Bài 2 : ( 2 đ) Rút gọn các biểu thức sau : (Mỗi câu đúng : 1 điểm)
(x + 3)2 – 2(x + 3)(x – 2) + (x – 2)2 =
= [(x + 3) – (x – 2)]2 (0.25)
= [x + 3 – x + 2]2 (0.25)
= [ 5]2 = 25 (0.25*2)

(x + 2)2 – (x – 4)(x + 4) =
= (x2 + 4x + 4) – (x2 – 16) (0.25 * 2)
= x2 + 4x + 4 – x2 + 16 (0.25)
= 4x – 20 (0.25 )




Bài 3: ( 2 đ)Tìm x, biết:( Mỗi câu đúng : 1 điểm)
x3 – 25x = 0.
x(x2 – 25) = 0 (0.25)

x = 0 hoặc x2 – 25 = 0
x = 0 (0.25)
x2 – 25 = 0
x =
5 (0.5)
Vậy x = 0; x =
5
x(x – 3) – 4x + 12 = 0.
x(x – 3) – 4(x – 3) = 0 (0.25)
(x – 3)(x