配套习题- 运用韦达定理求代数式或参数的值 -【青果学院】

1/5单选题

难度：

1.

已知x₁，x₂是方程的两根，则的值为（　　）

A	3
B	5
C	7
D

正确答案：QQ==

PGRpdj48aW1nIHNyYz0iaHR0cHM6Ly9wMi5xaW5nZ3VvLmNvbS9HMS9NMDAvMDAvOTgvckJBQ0ZGTU1hZG54ZFhoSEFBQUlaUmlVZ1dBMjM3LnBuZyIgZGF0YS1ja2Utc2F2ZWQtc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC8wMC85OC9yQkFDRkZNTWFkbnhkWGhIQUFBSVpSaVVnV0EyMzcucG5nIiBhbHQ9IiIgc3R5bGU9IndpZHRoOiA1NDVweDsgaGVpZ2h0OiA1NXB4OyI+PGJyPjwvZGl2Pg==

2/5单选题

难度：

2.

已知关于x的一元二次方程的两个实数根且，k的值为（）

A	8
B	-7
C	6
D	5

正确答案：RA==

PGRpdj48aW1nIHNyYz0iaHR0cHM6Ly9wMS5xaW5nZ3VvLmNvbS9HMS9NMDAvMDUvRDcvckJBQ0ZGTVFCc0t4MUtfbEFBQUoybm5NVHFNNDQ4LnBuZyIgZGF0YS1ja2Utc2F2ZWQtc3JjPSJodHRwczovL3AxLnFpbmdndW8uY29tL0cxL00wMC8wNS9ENy9yQkFDRkZNUUJzS3gxS19sQUFBSjJubk1UcU00NDgucG5nIiBhbHQ9IiIgc3R5bGU9IndpZHRoOiA1NDFweDsgaGVpZ2h0OiA2NXB4OyI+PGJyPjwvZGl2Pg==

3/5单选题

难度：

3.

已知x₁、x₂是方程x²+6x+3=0的两个实数根，则的值等于（　　）

A	-6
B	6
C	10
D	-10

正确答案：Qw==

PGRpdj48aW1nIHNyYz0iaHR0cHM6Ly9wMi5xaW5nZ3VvLmNvbS9HMS9NMDAvMjMvOEEvckJBQ0UxTU1hblNRZTFhbUFBQUp1akJYUG9FOTc3LnBuZyIgZGF0YS1ja2Utc2F2ZWQtc3JjPSJodHRwczovL3AyLnFpbmdndW8uY29tL0cxL00wMC8yMy84QS9yQkFDRTFNTWFuU1FlMWFtQUFBSnVqQlhQb0U5NzcucG5nIiBhbHQ9IiIgc3R5bGU9IndpZHRoOiA1MzNweDsgaGVpZ2h0OiA1NXB4OyI+PC9kaXY+

4/5单选题

难度：

4.

关于x的方程x²-ax+4=0（a＜0）的实数根是x_l、x₂，则的值为（　　）

A
B
C	-2a
D	2a

正确答案：QQ==

PGRpdj48aW1nIHNyYz0iaHR0cHM6Ly9wMS5xaW5nZ3VvLmNvbS9HMS9NMDAvMjMvODkvckJBQ0UxTU1haWJpNkVTWUFBQVhHa3FIQUdBNDA2LnBuZyIgZGF0YS1ja2Utc2F2ZWQtc3JjPSJodHRwczovL3AxLnFpbmdndW8uY29tL0cxL00wMC8yMy84OS9yQkFDRTFNTWFpYmk2RVNZQUFBWEdrcUhBR0E0MDYucG5nIiBhbHQ9IiIgc3R5bGU9IndpZHRoOiA1MjFweDsgaGVpZ2h0OiAxNTNweDsiPjwvZGl2Pg==

5/5单选题

难度：

5.

是方程的两个根，则代数式的值是（）

A	11
B
C	13
D

正确答案：Qg==

PGRpdj48aW1nIHNyYz0iaHR0cHM6Ly9wMS5xaW5nZ3VvLmNvbS9HMS9NMDAvMjMvODcvckJBQ0UxTU1hVG5SbDJyS0FBQUp0MlpLRGxFMjczLnBuZyIgZGF0YS1ja2Utc2F2ZWQtc3JjPSJodHRwczovL3AxLnFpbmdndW8uY29tL0cxL00wMC8yMy84Ny9yQkFDRTFNTWFUblJsMnJLQUFBSnQyWktEbEUyNzMucG5nIiBhbHQ9IiIgc3R5bGU9IndpZHRoOiAzMzVweDsgaGVpZ2h0OiA4MXB4OyI+PC9kaXY+