Need help with concept based questions

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In summary, the conversation discusses finding the value of f(x)-g(x) at x=4, given certain conditions on the functions f(x) and g(x). The person asking the question attempted to solve it themselves and got -6, but the published answer was 2. However, the question does not make sense as the domain is given as [0,2] but the value is being asked for at x=4. The conversation then shifts to discussing how to solve the problem, with one person suggesting integrating the functions f(x) and g(x) twice. The conversation ends with the person asking for clarification on their attempted solution and apologizing for posting in the wrong section.
  • #1
Deebu R
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Member warned that homework questions must go in the Homework sections
Let f(x) and g(x) be twice differentiable functions on [0,2] satisfying f"(x)=g"(x), f'(1)=4, g'(1)=6,f(2)=3 and g(2)=9.Then what is f(x)-g(x) at x=4 equal to?

I honestly have no idea how to do it.Please help.
 
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  • #2
I tried to do it myself and I got -6. This is actually a prev year question so when I checked online the answer was published as 2.
 
  • #3
The question makes no sense. You say the domain is ##[0,2]## but then ask the value at ##4##?
 
  • #4
micromass said:
The question makes no sense. You say the domain is ##[0,2]## but then ask the value at ##4##?
No. The value of f(x)-g(x) if x=4.
So value of f(4)-g(4).
 
  • #5
##f(4)## makes no sense if the domain is ##[0,2]##.
 
  • #6
This belongs in the homework section.

Also, you cannot evaluate the function at x = 4. However, I assume that's some kind of typo.

Start by integrating ##f(x) = g(x)## twice.
What do you know? Keep in mind: ##f' = g' \Rightarrow f = g + c##
 
  • #7
So, f"(x)=g"(x)
Integrating, f'(x)=g'(x)+c ===> (A)
f(x)=g(x)+cx+d =====(B)
Since f'(1)=4,
4=6+c (from A)
c=-2
Substituting this in B,
f(x)=g(x)+-2x+d
when x=2
f(2)=g(2)+-2(2)+d
3=9+-4+d
d=-2
Now using B,
f(x)=g(x)+-2(x)+-2
f(x)-g(x)=-2(x)-2
when x=4,
f(4)-g(4)= -8-2=-10?

what did I do wrong?Also sorry about the wrong section. I just joined 3 days ago so I thought science questions go to one section and math questions go to another section.
 

Related to Need help with concept based questions

What does it mean to have a concept based question?

A concept based question is a type of question that requires a deeper understanding of a particular concept or topic, rather than just recalling specific facts or information.

How can I improve my ability to answer concept based questions?

To improve your ability to answer concept based questions, it is important to have a solid understanding of the underlying concepts and principles. This can be achieved through studying, practice, and critical thinking. Additionally, breaking down the question into smaller parts and analyzing each part can help in finding the correct answer.

Are there any specific strategies for answering concept based questions?

Yes, there are several strategies that can be helpful when answering concept based questions. These include reading the question carefully, identifying key words and phrases, and connecting the question to your prior knowledge. Additionally, it can be helpful to eliminate any obviously incorrect answer choices and use process of elimination to narrow down the options.

Can I use outside resources to help me answer concept based questions?

Yes, it is generally acceptable to use outside resources such as textbooks, notes, and other reference materials to help answer concept based questions. However, it is important to make sure that you fully understand the concept and are not simply copying information without truly understanding it.

What should I do if I am still struggling with concept based questions?

If you are struggling with concept based questions, it can be helpful to seek assistance from a teacher, tutor, or classmate. You can also try breaking down the question further, reviewing the related material, or practicing with similar questions to improve your understanding and ability to answer these types of questions.

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