ลำดับเลขคณิตและลำดับเรขาคณิต

2,4,6,8,10

2,4,8,16,32

1,3,5,7,9,11

-2,-5,-8,-11,-13

5,10,15,20

1,4,16,64

-3,3,-3,3

3,9,27,81

15

10

5

3

1 , 2 ,3 , ...

2 , 5 , 8 , ...

100 , 50 , 25 , ...

7 , 14 , 26 , ...

$$a_n=a_1+(n−1)d$$

$$a_n=a_1-(n+1)d$$

$$a_n=a_1r\ ^{n-1\ }$$

$$a_n=a_1r\ ^{n+1\ }$$

1, 2, 4, 8, ...

1, 3, 5, 7, ...

3, 6, 9, 12, ...

3, 9, 27, 81, ...

1, -1, 1, -1, ...

1, 1, 1, 1, ...

x, x², x³, x⁴, ...

x, 2x, 3x, 4x, ...

0.1, 0.01, 0.001, 0.0001, ...

1.1, 2.1, 3.1, 4.1, ...