问题 填空题

已知函数f(x)=loga(x2+2ax+1)的值域为R,则a的取值范围是______.

答案

∵函数f(x)的值域是R

∴设真数t=x2+2ax+1,为关于x的二次函数,设其值域为M

则必定有(0,+∞)⊆M

∵二次函数t=x2+2ax+1图象是开口向上的抛物线

∴△=4a2-4≥0⇒a2≥1

又∵对数的底数为a,a>0且a≠1

∴a>1

故答案为:(1,+∞)

单项选择题

Information systems design is defined as those tasks that focus on the specification of a detailed computer-based solution. Typically, there are four systems design tasks for in-house development.

1) The first task is to specify(),which defines the technologies to be used by one, more, or all information systems in terms of their data, processes, interfaces, and network components. This task is accomplished by analyzing the data models and process models that are initially created during requirements analys16.

2) The next systems design task is to develop the (). The purpose of this task is to prepare technical design specifications for a database that will be adaptable to future requirements and expansion.

3) Once the database prototype has been built, the systems designer can work closely with system users to develop input, output and dialogue specifications. The()must be specified to ensure that the outputs are not lost, misrouted, misused, or incomplete.

4) The fourth design task involves packaging all the specifications from the previous design tasks into a set of specifications that will guide the() activities during the following phases of the systems development methodology.

Finally, we should() and update the project plan accordingly. The key deliverable should include a detailed plan for the construction phase that should follow

The()must be specified to ensure that the outputs are not lost, misrouted, misused, or incomplete.

A.format and layout

B.transaction details

C.additional instructions

D.internal controls

单项选择题