SPM 2019 Add Maths Paper 1, Question 3Quadratic Functions

Solved on video in English and Bahasa Melayu · 3 marks · Form 4, Quadratic Functions · 4:57 video

The question

The graph of a quadratic function f(x) = 3[2h - (x-1)²], where h is a constant, has maximum point (1, h-10). (a) State the value of h. (b) State the type of roots for f(x) = 0. Justify your answer.

[3 marks]

SPM 2019 Add Maths Paper 1, Question 3: the question as drawn in Eduly's video4:57

Step 1

Expand: f(x) = 3[2h - (x-1)²] = 6h - 3(x-1)² = -3(x-1)² + 6h.

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

Final answer

(a) h = −2; (b) no real roots, since (x − 1)² = −4 has no real solution

Where students lose marks

Watch out: substitute h = −2 back into f(x) before testing roots, and read the maximum as h − 10, not h + 10.

Watch every step of this question solved on video (4:57), with the reason behind each step and a box that checks your own answer.

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