Date | May 2013 | Marks available | 2 | Reference code | 13M.1.sl.TZ1.10 |
Level | SL only | Paper | 1 | Time zone | TZ1 |
Command term | Find | Question number | 10 | Adapted from | N/A |
Question
The straight line, L1, has equation \(2y − 3x =11\). The point A has coordinates (6, 0).
Give a reason why L1 does not pass through A.
Find the gradient of L1.
L2 is a line perpendicular to L1. The equation of L2 is \(y = mx + c\).
Write down the value of m.
L2 does pass through A.
Find the value of c.
Markscheme
\(2 \times 0 - 3 \times 6 \ne 11\) (R1)
Note: Stating \(2 \times 0 - 3 \times 6 = - 18\) without a conclusion is not sufficient.
OR
Clear sketch of L1 and A.
(R1)
OR
Point A is (6, 0) and \(2y - 3x = 11\) has x-intercept at \(- \frac{11}{3}\) or the line has only one x-intercept which occurs when x is negative. (R1) (C1)
\(2y = 3x + 11\) or \(y - \frac{3}{2}x = \frac{{11}}{2}\) (M1)
Note: Award (M1) for a correct first step in making y the subject of the equation.
\(({\text{gradient equals}}) = \frac{3}{2}(1.5)\) (A1) (C2)
Note: Do not accept 1.5x.
\((m = ) - \frac{2}{3}\) (A1)(ft) (C1)
Notes: Follow through from their part (b).
\(0 = - \frac{2}{3}(6) + c\) (M1)
Note: Award (M1) for correct substitution of their gradient and (6, 0) into any form of the equation.
(c =) 4 (A1)(ft) (C2)
Note: Follow through from part (c).
Examiners report
There were multiple acceptable reasons why the line did not pass through a given point (including numerically substituting values in the equation; drawing a graph or algebraically finding the x-intercept of the line). This was one of two reasoning marks in the paper.
There were multiple acceptable reasons why the line did not pass through a given point (including numerically substituting values in the equation; drawing a graph or algebraically finding the x-intercept of the line). This was one of two reasoning marks in the paper.
There were multiple acceptable reasons why the line did not pass through a given point (including numerically substituting values in the equation; drawing a graph or algebraically finding the x-intercept of the line). This was one of two reasoning marks in the paper.
There were multiple acceptable reasons why the line did not pass through a given point (including numerically substituting values in the equation; drawing a graph or algebraically finding the x-intercept of the line). This was one of two reasoning marks in the paper.