SPM 2019 Add Maths Paper 1, Question 5Progressions

Solved on video in English and Bahasa Melayu · 2 marks · Form 4, Progressions · 4:59 video

The question

It is given that the sum of the first m terms of an arithmetic progression is Sm = (k+1)/2 (a+7), such that k is a constant, a is the first term and 7 is the last term. (a) Express k in terms of m. (b) State the range of values of k.

[2 marks]

SPM 2019 Add Maths Paper 1, Question 5: the question as drawn in Eduly's video4:59

Step 1

The sum of the first n terms of an AP with first term a and last term l is Sn = n/2 (a+l).

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

Final answer

(a) k = m − 1 (b) k = 0, 1, 2, 3, … (k ≥ 0, k an integer)

Where students lose marks

Watch out: m counts terms, so it is a positive integer starting at 1. Do not let k go negative.

Watch every step of this question solved on video (4:59), with the reason behind each step and a box that checks your own answer.

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