Results 1 to 2 of 2

Thread: Math help?

  1. #1
    New Member
    Join Date
    Jan 2018
    HSC
    2019
    Gender
    Undisclosed
    Posts
    1
    Rep Power
    0

    Question Math help?

    These questions are out of the math in focus prelim book page 139


    a) Find the value of b in x^2 - 8x + b^2 is a perfect square. hence solve x^2 - 8x - 1 =0 by completing the square.

    ans is
    b=4;x= ±√17 +14 ≑ 8.12,-0,123

    I don't get what im being asked to do, also what does ≑ mean?

    b) |3y - 1| + |2y + 3| > 5

    ans is
    y<-1,Y>3/5


    Help me and i'll love you

  2. #2
    Taking a break! dan964's Avatar
    Join Date
    Jun 2014
    HSC
    2014
    Uni Grad
    2018
    Gender
    Male
    Location
    South of here
    Posts
    2,843
    Rep Power
    4

    Re: Math help?

    Quote Originally Posted by sugarcoated View Post
    These questions are out of the math in focus prelim book page 139


    a) Find the value of b in x^2 - 8x + b^2 is a perfect square. hence solve x^2 - 8x - 1 =0 by completing the square.

    ans is
    b=4;x= ±√17 +14 ≑ 8.12,-0,123

    I don't get what im being asked to do, also what does ≑ mean?

    b) |3y - 1| + |2y + 3| > 5

    ans is
    y<-1,Y>3/5


    Help me and i'll love you
    The symbol means approximately equal to. Perfect squares factorise to the form (ax+b)^2 (in this case a=1), that should start you off.
    Completing the square means you want to find something of the form (x+b)^2 = c


    [b] skeleton:
    Solve the equation 3y-1 + 2y + 3 = 5 that is 5y = 3
    -3y+1 + 2y + 3 = 5 that is -y=1.
    (There may be other cases e.g. 3y+1-2y-3=5 and -3y+1-2y-3=5, but these two are enough)
    etc.

    plot solutions on a number line and test to see if condition holds.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •