Oxford PAT 2015, Question 5

2015_paper__page5

Advertisements

10 thoughts on “Oxford PAT 2015, Question 5

  1. Hi, thanks a lot for this website which is proving extremely helpful! On the last line, why is it that (m-3) gives m >3 but (m-4)<0 gives m<4?

    1. We know that the quadratic (m-3)(m-4) = 0 when m = 3 or m = 4. But we are interested in the values of m for which it is less than 0. If you sketch the graph you’ll see that, when m is large and negative the quadratic is large and positive, when m is large and positive the quadratic is large and positive, and the quadratic is negative when 3 < m < 4.

  2. Hi,
    I am sorry, but why were you able to just cross off the 16 from in front of the parentheses in line 3? The same applies to subtracting the 4 from the first parentheses. Doesn´t that change the results of m?

    Thanks

    1. The first line has a quadratic in the form ax^2 + bx +c = 0.

      The second line is equivalent to b^2 – 4ac < 0, which is the condition for the quadratic in the first line to have no real roots.

Add your comments

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s