Sequences
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Good place to start:
https://www.purplemath.com/modules/series.htm
Sum of n terms of an arithmetic sequence = N/2 * (2A1 + (N-1)D)
where N-> number of elements in the sequence
A1-> first term of seq
D-> common difference between any 2 terms
Other formula variation for sum is:
Sum of AP terms = N/2 * ( A1+An)
where N-> no of terms in sequence
A1-> FIRST TERM OF SEQUENCE
An-> n the term of sequence
The n th element in an AP
An = A1 + (n-1)D (Here lowercase n is the nth element)
eg: 4TH ELEMENT
A4 = A1 + (4-1)D
A4 = A1 + 3D
With these formulas and some practice u can solve most problems in sequences.
https://www.purplemath.com/modules/series.htm
Sum of n terms of an arithmetic sequence = N/2 * (2A1 + (N-1)D)
where N-> number of elements in the sequence
A1-> first term of seq
D-> common difference between any 2 terms
Other formula variation for sum is:
Sum of AP terms = N/2 * ( A1+An)
where N-> no of terms in sequence
A1-> FIRST TERM OF SEQUENCE
An-> n the term of sequence
The n th element in an AP
An = A1 + (n-1)D (Here lowercase n is the nth element)
eg: 4TH ELEMENT
A4 = A1 + (4-1)D
A4 = A1 + 3D
With these formulas and some practice u can solve most problems in sequences.