Hey there! Sign in to join this conversationNew here? Join for free

distance between curve and line question thing Watch

    • Thread Starter
    Offline

    13
    ReputationRep:
    (im terrible with titles to my threads lmaooo)

    hey guys
    i need help with this question, ive thought about a variety of different ways to try and determine the answer, through integration or setting the equations equal to one another or even using Pythagoras to try and solve this, but to no luck unfortunately!

    how is a question like this supposed to be approached? I've used Desmos to see the graphs and without gettin too technical with the numbers, visually it appears the two graphs are closest where the curve is one unit deep (giving the point 1,5). however, when i tried solving what x would be when y = 5 for 5x-6, i do not get any of the answers available in the multiple choice

    any help would be greatly appreciated! thanks Attachment 693932693934Name:  image.jpg
Views: 10
Size:  191.6 KB
    Attached Images
     
    Online

    15
    ReputationRep:
    The question does not involve integration at all. What's the logic behind the working that you've done so far?
    • Thread Starter
    Offline

    13
    ReputationRep:
    (Original post by B_9710)
    The question does not involve integration at all. What's the logic behind the working that you've done so far?
    to be honest i don't really know what im doing, the working out is just random attempts to try and attain the answer. im not sure how to find the two closest points on each line
    Online

    15
    ReputationRep:
    You're finding the shortest vertical distance between the line and the curve.The vertical distance between the line and the curve will be given by the value of the y coordinate of the curve - the value of y coordinate of the line.
    Let us denote this distance function by  f which you should be able to see is given by  f(x)=3x^3+2-(5x-6) .
    Now you're finding the minimum value of this function - which you should know how to do - it's a quadratic function.
    • Thread Starter
    Offline

    13
    ReputationRep:
    (Original post by B_9710)
    You're finding the shortest vertical distance between the line and the curve.The vertical distance between the line and the curve will be given by the value of the y coordinate of the curve - the value of y coordinate of the line.
    Let us denote this distance function by  f which you should be able to see is given by  f(x)=3x^3+2-(5x-6) .
    Now you're finding the minimum value of this function - which you should know how to do - it's a quadratic function.
    ahh thank you very much! that made perfect sense and i understand this now, and also ended up getting the right answer, thank you
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Did TEF Bronze Award affect your UCAS choices?
    Useful resources

    Make your revision easier

    Maths

    Maths Forum posting guidelines

    Not sure where to post? Read the updated guidelines here

    Equations

    How to use LaTex

    Writing equations the easy way

    Student revising

    Study habits of A* students

    Top tips from students who have already aced their exams

    Study Planner

    Create your own Study Planner

    Never miss a deadline again

    Polling station sign

    Thinking about a maths degree?

    Chat with other maths applicants

    Can you help? Study help unanswered threads

    Groups associated with this forum:

    View associated groups
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

    Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

    Quick reply
    Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.