Kiểm tra 1 tiết

Họ và tên: ……………………………………………
Lớp 9
KIỂM TRA MỘT TIẾT CHƯƠNG IV
MÔN: ĐẠI SỐ 9
Ngày kiểm tra:……..
Điểm

Bài 1. Giải các phương trình sau
a. x2 + 6x + 8 = 0 b. c) x2 + 3x - 10 = 0 c. 4x2 – 9 = 0
Bài 2. Cho hàm số y = -x2 (P) và hàm số y = 2x – 3 (d)
Vẽ đồ thị hai hàm số trên cùng mặt phẳng tọa độ OXY
Xác định tọa độ giao điểm của (P)và (d)
Bài 3. Cho phương trình x2 + 6x – 7 = 0. Không giải phương trình hãy tính tổng 2 nghiệm x1+ x2 và tích 2 nghiệm x1.x2
Bài 4. Cho phương trình  x2 - 2mx + 2m - 1 = 0
Chứng tỏ phương trình luôn có nghiệm x1 , x2 với mọi m.
b. Tìm m để 2 nghiệm x1 , x2 của phương trình thỏa mãn hệ thức  x12 + x22 = 5
BÀI LÀM
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HƯỚNG DẪN CHẤM
Bài 1: Giải đúng mỗi câu 1 điểm
a. x2 + 6x + 8 = 0 b. c) x2 + 3x - 10 = 0 c. 4x2 – 9 = 0
x1= -2, x2 = -4 x1= 2, x2 = -5 x1= -3/2, x2 = 3/2
Bài 2. a.Vẽ đúng đồ thi mỗi hàm số 1 điểm
Phương trình hoành độ : - x2 -2x +3 = 0
X1 = 1. Suy ra y1= -1
x2 = -3. Suy ra y1= -9 (1 điểm)
Bài 3. x2 + 6x – 7 = 0.∆ =36 + 28 =64 >0 (0,5 điểm)
x1+ x2 = - 6, x1. x2 = -7 (1 điểm)
Bài 4.a. ∆’ = (m2 – 2m + 1), ∆’ = (m-1)2≥0 với mọi m. Vậy pt có nghiệm với mọi m (1,5điểm)
b. Tính được m=3/2 và m = -1/2( 1 điểm)