Higher November 2024 Paper 2 Q17
17 Straight line \(LM\) has equation \(\quad y = 4x - 7\)
Straight line \(ST\) has equation \(\quad y = \dfrac{9 - x}{4}\)
Are the lines \(LM\) and \(ST\) perpendicular?
Tick a box.
- Yes
- No
Give a reason for your answer. [2 marks]
| Answer | Mark | Comments |
|---|---|---|
| (gradient \(LM\) =) 4 or (gradient \(ST\) =) \(-\dfrac{1}{4}\) | M1 | oe do not allow inclusion of \(x\) unless recovered |
| Yes and valid reason | A1 | valid reasons include \(-\dfrac{1}{4}\) is the negative reciprocal of 4 \(-\dfrac{1}{4} \times 4 = -1\) \(-1 \div \left(-\dfrac{1}{4}\right) = 4\) |