SPM 2017 Add Maths Paper 1, Question 11Quadratic Functions

Solved on video in English and Bahasa Melayu · 4 marks · Form 4, Quadratic Functions · 3:06 video

The question

The quadratic function f is defined by f(x) = x² + 4x + h, where h is a constant. (a) Express f(x) in the form (x + m)² + n, where m and n are constants. (b) Given the minimum value of f(x) is 8, find the value of h.

[4 marks]

SPM 2017 Add Maths Paper 1, Question 11: the question as drawn in Eduly's video3:06

Step 1

Complete the square: x² + 4x = (x+2)² - 4, so f(x) = (x+2)² - 4 + h. In the form (x+m)²+n, this gives m = 2 and n = h - 4.

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

Final answer

(a) f(x) = (x + 2)² + h − 4, m = 2, n = h − 4; (b) h = 12

Where students lose marks

Watch out: the minimum value is +8, so h − 4 = 8. Writing −4 + h = −8 is a sign error.

Watch every step of this question solved on video (3:06), with the reason behind each step and a box that checks your own answer.

Start 7 days freeAlready a member? Watch it now

No card. Every past-year question on video, in English and BM.

All questions in SPM 2017 Paper 1

Quadratic Functions: lessons and every past-year question

Baca dalam Bahasa Melayu

More Quadratic Functions questions

Questions are re-typeset by Eduly for study and commentary. Eduly is not affiliated with Lembaga Peperiksaan Malaysia or the Ministry of Education.