齿轮的分度圆直径等于模数和齿数的（）。 A.和 B.差 C.商 D.乘积_爱下问搜题

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问题单项选择题

齿轮的分度圆直径等于模数和齿数的（）。

A.和

B.差

C.商

D.乘积

答案

参考答案：D

解答题

已知关于x的一元二次方程x²+2（k-1）x+k²-1=0有两个不相等的实数根x₁，x₂．

（1）求实数k的取值范围；

（2）若3（x₁+x₂）=x₁x₂，求k的值．

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The 30th Olympic host city, London is opening its arms to the world. It is the capital city of the UK .It has the history of 2000 years. Today London is a big city with 7 million people. They are from all parts of the world. Their ways of life are not the same but harmonious(和谐的).Their favorite food is pie and mashed potatoes.

London
The capital 小题1: of the UK	The 30^th Olympic host city
The history of London	小题2: years
The population (人口) of London	小题3: million
The ways of life	小题4: but harmonious
The favorite food	小题5: and mashed potatoes