问题 解答题

已知函数y ="(2m+1)" x+ m-3

(1) 若函数图象经过原点,求m的值

(2) 若函数图象在y轴的交点的纵坐标为-2,求m的值

(3)若函数的图象平行直线y=3x–3,求m的值  

(4)若这个函数是一次函数,且y随着x的增大而减小,求m的取值范围.

答案

(1)m=3;(2)m=1

(3) m=1;(4) m<

题目分析:(1)若函数图象经过原点,m-3=0,解得m=3.

(2)依题意知,当x=0时,y=(2m+1) x+ m-3=-2。解得:m=1.

(3)依题意知,函数y ="(2m+1)" x+ m-3平行于直线y=3x–3,设函数y ="(2m+1)" x+ m-3为直线y=3x–3上下平移所得平行线,设x=1时,则y=3m-2,即(1,3m-2),x=0时,y=m-3,即(0,m-3)而直线y=3x–3则经过(1,0)(0,-3)可得m-3-(-3)=3m-2,解得m=1.

(4)若这个函数是一次函数,且y随着x的增大而减小,可知k<0,2m+1<0.解得m<

点评:本题难度中等。主要考查学生对一次函数各知识点的掌握。属于中考常见题型,应加强训练,同时,注意数形结合的应用。

解答题
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Some people bring out the best in you in a way that you might never have fully realized on your own.My mother was one of those people.

My father died when I was one-year-old.While I was growing up, we led a very hard life, but my mom gave me a lot of love.Each night, she seated me on her lap and, spoke the words that would change my life, "Kemmons, you are sure to be a great man and you can do anything in life if you work hard enough to get it."

At fourteen, I was hit by a car and the doctors said that I would never walk again.Every night my mother spoke to me in her gentle, loving voice, telling me whatever those doctors said, I could walk again if I wanted to.She drove that message so deep into my heart that I finally believed her.A year later, I walked on my own to school!

When the Great Depression broke out, my mother lost her job.Then I left school to support the two of us.At that moment I decided never to be poor again.

Over the years, I experienced a lot of business success.But the real turning point happened on a vacation I took with my wife and five kids in 1951.I was dissatisfied with the second-class hotels available for families and was very angry that they charged an extra $2 for each child.That was too expensive for an ordinary American family.I told my wife that I was going to open a motel (汽车旅馆) for families that would never charge extra money for children.Many people did not believe me at that time.

Not surprisingly, mom was my strongest supporter.As in any business, I experienced a lot of difficulties.But with my mom's words in my heart, I never doubted I would succeed.Fifteen years later, I had the largest hotel system in the world—Holiday Inn.In 1979 my company had 1,759 inns in more than fifty countries with an income of $l billion a year.

You may not have started out life in the best situations.But if you find a task in life worth working for and believe in yourself, nothing can stop you.

小题1:What Kemmon's mother often told him during his childhood was____.

A.caring

B.moving

C.encouraging

D.interesting小题2:Who played the most important role in making the author walk back to school again?

A.Doctors.

B.Nurses.

C.His friend.

D.His mom.小题3:What caused Kemmon to start a motel by himself?

A.His terrible experience in the hotel.

B.His wife's suggestion.

C.His previous business success.

D.His mom's support.小题4:Which of the following best describes Kemmon's mother?

A.Modest, helpful and hard-working.

B.Loving, supportive and strong-willed.

C.Careful, beautiful and helpful.

D.Strict, sensitive and supportive.小题5:Which of the following led to Kemmon's success?

A.Self-confidence, hard work, higher education and a poor family.

B.Mom's encouragement, clear goals, self-confidence and hard work.

C.Clear goals, mom's encouragement, a poor family and higher education.

D.Mom's encouragement, a poor family, higher education and opportunities.