SPM 2018 Add Maths Paper 1, Question 6
Solved on video in English and Bahasa Melayu · 4 marks · 4:41 video
The question
It is given that L = 4t - t² and x = 3 + 6t. (a) Express dL/dx in terms of t. (b) Find the small change in x, when L changes from 3 to 3.4 at the instant t = 1.
[4 marks]
4:41Step 1
Differentiate L = 4t - t² with respect to t: dL/dt = 4 - 2t.
5 more steps, each with the reason for it, in the full solution
Final answer
(a) dL/dx = (2 − t)/3; (b) δx = 1.2
Where students lose marks
Watch out: δx = δL ÷ (dL/dx), so invert the gradient. Substitute t = 1 only after differentiating, never before.
Watch every step of this question solved on video (4:41), with the reason behind each step and a box that checks your own answer.
No card. Every past-year question on video, in English and BM.
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