SPM 2019 Add Maths Paper 1, Question 11Linear Law

Solved on video in English and Bahasa Melayu · 3 marks · Form 4, Linear Law · 5:07 video

The question

The variables x and y are related by the equation y/x = px² - qx, where p and q are constants. Diagram 3.1 and Diagram 3.2 show the straight line graphs obtained by plotting the relations from the equation. Express p in terms of q.

[3 marks]

SPM 2019 Add Maths Paper 1, Question 11: the question as drawn in Eduly's video5:07

Step 1

Divide y/x = px² - qx by x²: y/x² = px - q. This is linear in x with gradient p and Y-intercept -q, matching Diagram 3.1 (Y = y/x² vs X = x).

Why this step

The graph's axes tell us the target form. Diagram 3.1 plots y/x² against x, so we reshape the equation into Y = mX + c with those variables.

5 more steps, each with the reason for it, in the full solution

Final answer

p = (q + 18)/6

Where students lose marks

Watch out: Diagram 3.1's intercept is −q, but Diagram 3.2's intercept is p (its gradient is −q). Don't mix up gradient and intercept.

Watch every step of this question solved on video (5:07), with the reason behind each step and a box that checks your own answer.

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