Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    0
    ReputationRep:
    Find the range of values of k for which x^2 +k(x+2) +3(x+1) >0 for all real values of x.
    Offline

    14
    ReputationRep:
    try to solve as you usually do with double brackets!
    >0 take as = 0 but do write >0 when solving
    Offline

    2
    ReputationRep:
    try to get it in the form ax^2+bx+c>0 (quadratic equation), determine its discriminant Δ which is a function of k. Then solve Δ<0
    Furthermore, working with double brackets keep in mind that not only the product of two positive numbers is greater than zero, but also the product of two negative ones.
    Offline

    15
    ReputationRep:
    (Original post by fatima1998)
    try to solve as you usually do with double brackets!
    >0 take as = 0 but do write >0 when solving
    This can lead to problems with quadratic inequalities.
    Offline

    14
    ReputationRep:
    (Original post by B_9710)
    This can lead to problems with quadratic inequalities.
    but isn't this just a simple algebra but they put that sign to make it complicated!
    Offline

    22
    ReputationRep:
    (Original post by fatima1998)
    but isn't this just a simple algebra but they put that sign to make it complicated!
    Not at all!
    Offline

    14
    ReputationRep:
    (Original post by Zacken)
    Not at all!
    oops!! i misunderstood the question
    i thought the question is to find the value of x but it's values of the k
 
 
 
  • 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
    Brexit voters: Do you stand by your vote?
    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

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