题干

在函数y=
x
+
2
5
x
中,自变量x的取值范围是(   )

A:x≠0

B:x≤2且x≠0

C:x≥-2且x≠0

D:x≥-2

上一题 下一题 0.0难度 选择题 更新时间:2018-06-08 10:33:59

答案(点此获取答案解析)

C

同类题5

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

    Taking a math test can be pretty stressful. Even if you know the material, you can still get the problem wrong. ____ Therefore you'll improve your grades, as well as your math skills.

    Write it out

    You can also check a math problem by writing everything out on paper. ____ Writing out math problems reduces your chances of missing anything to the lowest possible level, which is a common cause of incorrect answers.

    ____

    Make sure your answers work by doing the opposite procedure of what your problem calls for, including the answer you got the first time around. In other words, you would use the opposite of this addition problem—subtraction (减法)—to determine whether your answer is the correct one.

    Plug in(代入)

    You may find that a variable isn't good enough or have a problem where you have to solve for a variable (变量). ____ This is the only real way to assure yourself that the answer you've found is correct.

    ____

    If the result of a problem seems to make no sense, it indicates that the answer is incorrect. For example, if you get an answer in the millions and you know it should be in the thousands, you've likely misplaced a point. Go back through the work on your paper to make sure all of your formulas and calculations are correct. If everything looks okay, do the problem again and compare the result of the second try to what you've got on the first try.

A. Do the opposite.

B. Correct the answers.

C. Plug the variable in the equation (方程) to check it out.

D. Knowing how to go through your math test and checking your work can save you from handing in a test full of mistakes.

E. It also helps you to figure out everything after you have already finished the test.

F. Check for a reasonable answer

G. This helps you to know what information you have and what information you need to solve.