SPM 2018 Add Maths Paper 1, Question 19Quadratic Functions

Solved on video in English and Bahasa Melayu · 3 marks · Form 4, Quadratic Functions · 3:53 video

The question

Firdaus has a rectangular plywood with a dimension 3x metre in length and 2x metre in width. He cuts part of the plywood into a square shape with sides of x metre to make a table surface. Find the range of values of x if the remaining area of the plywood is at least (x²+4) metre².

[3 marks]

SPM 2018 Add Maths Paper 1, Question 19: the question as drawn in Eduly's video3:53

Step 1

The original rectangular plywood has area = length x width = 3x times 2x = 6x² (metre squared).

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

Final answer

x ≥ 1

Where students lose marks

Watch out: the remaining area is 5x², not 4x². Also reject x ≤ −1, because x is a length.

Watch every step of this question solved on video (3:53), with the reason behind each step and a box that checks your own answer.

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