Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
Hi there,
There is an issue with role permissions that is being worked on at the moment.
If you are having trouble with access or permissions on regional forums please post here to get access: https://www.boards.ie/discussion/2058365403/you-do-not-have-permission-for-that#latest

Maths Question Help!!

  • 07-10-2018 12:20am
    #1
    Registered Users, Registered Users 2 Posts: 134 ✭✭


    This isn't homework. I'm studying for my upcoming Maths Halloween Test :pac:

    I was practising some questions and came across this one

    If 4x - 3 is a factor of 4x^3 - 23x^2 + px + 27, find the value of p.

    I got to (p-15)/4 + 27 but idk if that is right and if it is idk what to do from that point on

    Thank You


Comments

  • Registered Users, Registered Users 2 Posts: 612 ✭✭✭JoseJones


    naxmax9 wrote: »
    This isn't homework. I'm studying for my upcoming Maths Halloween Test :pac:

    I was practising some questions and came across this one

    If 4x - 3 is a factor of 4x^3 - 23x^2 + px + 27, find the value of p.

    I got to (p-15)/4 + 27 but idk if that is right and if it is idk what to do from that point on

    Thank You

    Show me what you have done so far, then I'll show you what I have... For an answer I have got p = -21


  • Registered Users, Registered Users 2 Posts: 36 Tropical.ing


    Make the other factor equal to ( x^2 + kx - 9 ), multiply both factors together, find the value of k and sub it into the equation you get for p to find the value of p

    Edit: after attempting the question with this method, I also got p = -21


  • Registered Users, Registered Users 2 Posts: 8 MathsNerd78


    A bit late now but here goes anyway. If 4x-3 is a factor then 3/4 is a root. Simply sub in 3/4 for x and put the expression equal to zero (because a root will satisfy this equation). You get 4(27/64)-23(9/16)+p(3/4)+27=0. Multiply across by 64 and solve. You'll get p=-21.


Advertisement