3 Đề kiểm tra 15 phút môn Đại số Lớp 8

ĐỀ 1 Câu 1: Biểu diễn tập nghiệm của mỗi bất phương trình sau trên trục số: x < 3 ; x ≥ – 4 Câu 2: a) Cho a < b. Chứng tỏ a + 3 < b + 3; b) Cho a > b. Chứng tỏ 5a > 5b c) Cho a < b. Chứng tỏ 2 – 3a > 2 – 3b; d) Cho a > b. Chứng tỏ 4a + 5 > 4b +2 Câu 3: Giải các bất phương trình và biểu diễn trên trục số: a) x – 2 > 0 ; b) 3x + 9 ≤ 0 ;

Câu 4: Giải các bất phương trình sau: a) 4x – 2 ≤ 3x + 1 b)

2?― 5

3 ≥

5 ― ?

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ĐỀ 2 Câu 1: Biểu diễn tập nghiệm của mỗi bất phương trình sau trên trục số: x > 2 ; x ≤ – 3 Câu 2: a) Cho a > b. Chứng tỏ a + 2 > b + 2; b) Cho a < b. Chứng tỏ – 2a > – 2 b c) Cho a < b. Chứng tỏ 3a + 1 < 3b + 1; d) Cho a > b. Chứng tỏ 6b + 5 > 6b + 2 Câu 3: Giải các bất phương trình và biểu diễn trên trục số: a) x + 4 > 0 ; b) 3x – 6 < 0 ;

Câu 4: Giải các bất phương trình sau: a) 4x + 2 ≥ 3x + 4 b)

3?+ 2

6 ≤

4 ― ?

5 _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ …