题干

在化简二次根式时,我们有时会碰上如
5
3
2
3
2
3
+
1
这样的式子,其实我们还可以将其进一步化简:

5
3
= ××
5
3
3
3
=
5
3
3 ;(一)

2
3
= ××
2
3
3
3
=
6
3
(二)

2
3
+
1
= ×
2
(
3
1
)
(
3
+
1
)
(
3
1
)
=
2
(
3
1
)
(
3
)
2
1
2
= 3 ﹣1(三)

以上这种化简的步骤叫做分母有理化.

2
3
+
1
还可以用以下方法化简:

2
3
+
1
=
3
1
3
+
1
=
(
3
)
2
1
2
3
+
1
=
(
3
+
1
)
(
3
1
)
3
+
1
= 3 ﹣1(四)
上一题 下一题 0.0难度 选择题 更新时间:2017-11-05 07:02:52

答案(点此获取答案解析)

同类题1

用酵母菌使葡萄汁产生葡萄酒,当酒精含量达到12%~16%时,发酵就停止了.有关叙述不正确的是(  )

同类题2

阅读理解

    People with an impulsive personality refer to those who tend to do things without considering the possible dangers or problems first. According to a new study by researchers at the University of Georgia, such people may be more likely to have food addiction. The study found that people exhibiting impulsive behavior weren't necessarily overweight, but impulsiveness was related to a direct relationship with food, and therefore, less healthy weight.

    Food addiction has been compared to addictive drug use. Studies have linked the dopamine (多巴胺) release that occurs after tasting delicious food to the dopamine release that happens when people consume other addictive substances.

    Impulsive behavior involves several personality traits (特点). Two of these traits, known as negative urgency and lack of perseverance, were particularly associated with food addiction and high BMI (身体质量指数) during the study.

    Negative urgency is characterized by the tendency to behave impulsively when experiencing negative emotions. Some people might drink alcohol or take drugs. For others, it could mean eating to feel better. Lack of perseverance is when a person has a hard time finishing hard or boring tasks. People with a lack of perseverance might have difficulty attempting to change addictive eating behavior, which could also cause obesity.

    “Impulsiveness might be one reason why some people eat in an addictive way despite motivation to lose weight,” said Dr. Ashley Gearhardt, a clinical psychologist. He was involved in developing the Yale Food Addiction Scale in aid of those people. “We are theorizing that if food addiction is really a thing, then our measure, the Yale Food Addiction Scale, should be related to helping control impulsive action,” said Gearhardt.

    Clinical psychologist Dr. James MacKillop, whose lab was conducting the study, believes that therapies used to treat addictive drug behavior could help people who suffer from addictive eating habits.

    “Most of the programs for weight loss at this point focus on the most obvious things, which are clearly diet and exercise,” MacKillop said. “It seems that managing strong desires to eat would naturally fit in with the skills a person would need to eat healthily.”

同类题3

亚洲大多数居民属于(   )

同类题4

如图,已知棋子“卒”的坐标为(﹣2,1),棋子“马”的坐标为(1,1),则棋子“炮”的坐标为(  )


同类题5

石灰石是许多化工生产的原料之一,但制取下列物质不需要到石灰石的是(  )
小学学科试题库
初中学科试题库
高中学科试题库