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

core 1 Watch

Announcements
    • Thread Starter
    Online

    12
    ReputationRep:
    Solve the equation x^6 + 26x^3 -27=0
    i substituted x^6 for x^2,
    so i'm trying to factorise x^2+26x-27=0?? i cant seem to factorise it.
    Offline

    1
    ReputationRep:
    You're on the right track. You can factorise x^2+26x-27=0 by finding two numbers whose sum is 26x and whose product is -27x^2.
    Offline

    18
    ReputationRep:
    (Original post by Chelsea12345)
    Solve the equation x^6 + 26x^3 -27=0
    i substituted x^6 for x^2,
    so i'm trying to factorise x^2+26x-27=0?? i cant seem to factorise it.
    You can't find two numbers that multiply to give -27 and add to give 26 ?????
    By considering every positive integer starting at 1, Systematically make a list of factor pairs
    1 and -27
    3 and -9
    9 and -3
    Etc

    Posted from TSR Mobile
    Offline

    9
    ReputationRep:
    (Original post by Chelsea12345)
    Solve the equation x^6 + 26x^3 -27=0
    i substituted x^6 for x^2,
    so i'm trying to factorise x^2+26x-27=0?? i cant seem to factorise it.
    It can be factorised. I don't really want to give you the answer, but 27 and 1.
    • Community Assistant
    • Welcome Squad
    Online

    20
    ReputationRep:
    (Original post by Chelsea12345)
    Solve the equation x^6 + 26x^3 -27=0
    i substituted x^6 for x^2,
    so i'm trying to factorise x^2+26x-27=0?? i cant seem to factorise it.
    You know, completing the square is always an option. You don't always have to give up just because you can't spot the shortcut.
    Online

    20
    ReputationRep:
    if you can't spot the factors you could complete the square & solve ?
    • Thread Starter
    Online

    12
    ReputationRep:
    (Original post by RDKGames)
    You know, completing the square is always an option. You don't always have to give up just because you can't spot the shortcut.
    i wasn't aware that factorising is a shortcut and even so, i've been repeatedly trying to factorise the equation using different numbers for a quite a while before i posted the question. The thought of completing the score hasn't crossed my mind but implying that i'm giving up on the question is uncalled for.
    Online

    20
    ReputationRep:
    for this example it would be quite hard to use the formula to solve, but completing the square is not too bad.
    Offline

    18
    ReputationRep:
    (Original post by emduck)
    It can be factorised. I don't really want to give you the answer, but 27 and 1.
    correction 27 and -1

    (Original post by gdunne42)
    You can't find two numbers that multiply to give -27 and add to give 26 ?????


    Posted from TSR Mobile
    Offline

    9
    ReputationRep:
    (Original post by Emz99)
    correction 27 and -1
    I know. (x-1)(x+27)=0 x=1 or x=-27 but I just gave the factors that made up 27, I assumed they'd be able to work out the rest. I guess I should've probably said 27 and -1

    Posted from TSR Mobile
 
 
 
  • 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
    Will you be richer or poorer than your parents?
    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.