Urgent Maths Homework :(

This is a discussion on Urgent Maths Homework :( within the A Brief History of Cprogramming.com forums, part of the Community Boards category; Hey, I aint to good at maths and need some help on basic algebra lol. Can someone explain to me ...

  1. #1
    Registered User (TNT)'s Avatar
    Join Date
    Aug 2001
    Location
    UK
    Posts
    339

    Unhappy Urgent Maths Homework :(

    Hey,

    I aint to good at maths and need some help on basic algebra lol.

    Can someone explain to me the method of Removing the brakets and simplifying this:


    (a - 7)(a +5)

    The answer is a2 - 2a - 35 (a2 is a squared)

    Please Help me understand how you get that

    Thanks alot
    TNT
    TNT
    You Can Stop Me, But You Cant Stop Us All

  2. #2
    ....
    Join Date
    Aug 2001
    Location
    Groningen (NL)
    Posts
    2,386
    (a + b)(c + d) = ac + ad + bc + bd

    At Dutch schools we call this method: Vogelbekje. In English it is something like "mouth of a bird". If you draw lines from a to c, a to d and then b to c and b to d. The first two lines above the formula and the last two under the formula, you will notice why.

  3. #3
    It's full of stars adrianxw's Avatar
    Join Date
    Aug 2001
    Posts
    4,831
    (Term1 + Term2) (Term3 + Term4)

    =

    (Term1 * Term3) + (Term1 * Term4) + (Term2 * Term3) + (Term2 * Term4)

    Obviously, some of the "+" are "-" depending on the signs in your original equation.

    In your case...

    T1 * T2 is (a * a) i.e. a^2
    T1 * T3 is (a * 5)
    T2 * T3 is (-7 * a)
    T2 * T4 is (-7 * 5) i.e. -35

    (a * 5) + (-7 * a) simplifies to -2a

    So a^2 - 2a -35

    *** EDIT ***

    Don't you just hate it when someone is typing their answer at the same time as you!!!
    Wave upon wave of demented avengers march cheerfully out of obscurity unto the dream.

  4. #4
    _B-L-U-E_ Betazep's Avatar
    Join Date
    Aug 2001
    Posts
    1,412
    the quantity of a-7 times the quantity of a+5

    When you have 'quantity of' with multiplication and division, you have to make sure that you perform all of the multiplication and division before you do any addtion and subtraction (common in all mathematics).

    In your problem...

    (a-7)(a+5)

    you start with the first digit (or representative thereof) which is +a in this case. You take this and multiply it by the other side...

    (a)(a+5)

    to get

    a^2 + 5a ... (or a squared plus five a )

    then you do the same with the negative seven...

    (-7)(a+5)

    to get

    -7a - 35 ... (or negative seven a plus a negative 35)

    put them all together

    a^2 + 5a - 7a - 35 (a squared plus five a plus a negative seven a plus a negative 35

    combine the like terms which are 5a and -7a to get -2a

    and you are left with

    a^2 - 2a - 35

    does that help any?


    edit... yeah I hate it... especially when you type more and two people beat you to it
    Blue

  5. #5
    Registered User (TNT)'s Avatar
    Join Date
    Aug 2001
    Location
    UK
    Posts
    339
    Ok,

    Thanks alot guys

    Cheers
    TNT
    TNT
    You Can Stop Me, But You Cant Stop Us All

  6. #6
    Registered User
    Join Date
    Nov 2001
    Posts
    202
    I was always taught to use FOIL for multiplying 2 bi-nomials(sp?)
    you multipy the F(irst) part of each parenthese then the outer most 2, followed by the inner most two, and finally the second one in each parenthese.
    ie...
    (1+2)*(3+4)=1*3 + 1*4 + 2*3 + 2*4

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. need urgent Homework help
    By zakimasmoudi in forum C Programming
    Replies: 2
    Last Post: 11-11-2007, 03:54 PM
  2. Urgent homework help for NEWBIE
    By Kazasan in forum C++ Programming
    Replies: 12
    Last Post: 10-11-2004, 05:23 PM
  3. Urgent - Help - Homework Question
    By Sway2 in forum C++ Programming
    Replies: 12
    Last Post: 10-04-2002, 02:35 PM
  4. maths in a program
    By anthonye in forum C Programming
    Replies: 2
    Last Post: 05-24-2002, 10:08 AM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21