Question

What is the sequence of 100,99,97,94,90

Answer 1

Subtract 1 from 100. Next subtract 2 from that answer. Then subtract 3 & so on. 
Un = 100 - n*(n-1)/2 for n = 1, 2, 3, . . 

Answer 2

Answer:

The sequence form is  $100-\frac{n(n-1)}{2}$ where, n is the natural number.      

Step-by-step explanation:

Given : Sequence 100,99,97,94,90

To find : What is the sequence ?

Solution :

We have to determine the pattern between them as,

100-0=100

100-1=99

100-3=97

100-6=94

100-10=90

So, We have to create the pattern of 0,1,3,6,10

i.e. $\frac{n(n-1)}{2}$

Therefore, The sequence form is  $100-\frac{n(n-1)}{2}$ where, n is the natural number.

Verification :

For n=1, $100-\frac{1(1-1)}{2}=100-0=100$

For n=2, $100-\frac{2(2-1)}{2}=100-1=99$

For n=3, $100-\frac{3(3-1)}{2}=100-3=97$

For n=4, $100-\frac{4(4-1)}{2}=100-6=94$

For n=5, $100-\frac{5(5-1)}{2}=100-10=90$