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 all,
Vanilla are planning an update to the site on April 24th (next Wednesday). It is a major PHP8 update which is expected to boost performance across the site. The site will be down from 7pm and it is expected to take about an hour to complete. We appreciate your patience during the update.
Thanks all.

Stumped by 10 year old's maths homework question. Help!

Options
  • 05-02-2020 9:15pm
    #1
    dark crystal
    Registered Users Posts: 10,962 ✭✭✭✭


    The product of two numbers is 40. The difference between them is 3. What are the two numbers?

    I cannot for the life of me work it out...can anyone help??


Comments

  • Options
    #2
    is_that_so
    Registered Users Posts: 32,136 ✭✭✭✭is_that_so


    I means multiplied by - for example 4X3 and 12 is the product.


  • Options
    #3
    un5byh7sqpd2x0
    Closed Accounts Posts: 1,862 ✭✭✭un5byh7sqpd2x0


    5 and 8


  • Options
    #4
    I Am The Law
    Registered Users Posts: 657 ✭✭✭I Am The Law


    5 x 8


  • Options
    #5
    ectoraige
    Registered Users Posts: 2,100 ✭✭✭ectoraige


    dark crystal wrote: »
    The product of two numbers is 40. The difference between them is 3. What are the two numbers?

    I cannot for the life of me work it out...can anyone help??

    Product means multiplication, so what two numbers multiplied together make 40?

    There's 1x40, 2x20, 4x10, and 5x8.

    Difference means substraction so which pair had a difference of 3?

    5 and 8 is the answer


  • Options
    #6
    is_that_so
    Registered Users Posts: 32,136 ✭✭✭✭is_that_so


    Seriously people, doing the child's homework by giving up the answer?! I dunno.:)


  • Advertisement
  • Options
    #7
    dark crystal
    Registered Users Posts: 10,962 ✭✭✭✭dark crystal


    Thank you so much everyone! I was trying to work out every combination of numbers that added up to 40, but multiplication never entered my clearly empty head.

    And I'm usually so good at Countdown...:o


  • Options
    #8
    Yakuza
    Registered Users Posts: 5,141 ✭✭✭Yakuza


    -8 and -5 also works :) (not sure it's appropriate for a 10-year old though :))

    To work it out analytically instead of brute force:
    Let x be the lower number, so x+3 will be the higher one.
    x*(x+3) = 40, or x²+3x - 40 = 0.
    Banging this into the good old Quadratic Equation formula (with a=1, b=3 and c = -40) yields -8 and 5 for x (so the other number being -5 or 8).


Advertisement