Formula Add Math chapter 1 form 5

Assalamualaikum . Hari ni saya nak berkongsi sedikit ilmu tentang add math . But hanya formula sahaja :) 

Lesson 1 : Additional Mathematics form 5 chapter 1

CHAPTER 1 : ARITHMETIC PROGRESSION . 

Definition :

Tn : The nth term .
Sn : The sum of the first nth terms
a : The first terms = T1
d : common difference = Tn-Tn-1 = T2 - T1 or T2 - T3 ........

Formula:

• Tn = a + (n-1)d: To get the nth term, you need to have the first term, a or T1 and d
• Sn = n( 2a + (n-1)d)/2 : To get the sum of the first n terms you need to know, a or T1 and d
• Sn = n(a + Tn)/2 : To get the sum first n terms you need to know a or T1 and Tn. You can get this formula by using equation 1 and 2 above.
• Tn = Sn - Sn-1 : To get the nth term, you subtract the sum of the first n terms with the sum of the first (n-1) term.
• Sn-m = Sn - Sm : To get the the sum from (m+1)th term to nth term, you subtract the sum of the first n terms with the sum of the first m terms. Example S8 = S15- S7 where S8 = T8 + T9 + T10...+ T14 + T15.

Sekian terima kasih :)