SPM 2017 Add Maths Paper 1, Question 19Linear Law

Solved on video in English and Bahasa Melayu · 3 marks · Form 4, Linear Law · 3:55 video

The question

The variables x and y are related by the equation y = x + r/x², where r is a constant. Diagram 8 shows a straight line graph obtained by plotting (y - x) against 1/x². The line passes through the point (h/2, 5p). Express h in terms of p and r.

[3 marks]

SPM 2017 Add Maths Paper 1, Question 19: the question as drawn in Eduly's video3:55

Step 1

Rearrange y = x + r/x² as (y - x) = r * (1/x² + 0, which is a straight line Y = mX + c with Y = (y-x), X = 1/x², gradient m = r, and intercept c = 0.

Why this step

Match it to Y = mX + c. There is no constant term, so c = 0 and the line goes through the origin. Don't add an extra intercept.

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

Final answer

h = 10p/r

Where students lose marks

Watch out: the line passes through the origin, so c = 0. Don't add an intercept, and divide by r carefully when isolating h.

Watch every step of this question solved on video (3:55), with the reason behind each step and a box that checks your own answer.

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