Answer:
<u>a(n)=80*(9/10)^(n-1)</u>
Step-by-step explanation:
I think u r confused 
this sequence is geometric not arithmetic
HOw we know that ??
when we get a common difference  <u>that must Be equal  </u>
d=72-80=-8  not equal to  d=64.8-72=-7.2
So it is not arithmetic 
but when we get the common ratio that also must <u>be equal </u>
r=72/80=9/10  equal to   r=64.8/72=9/10
So it is geometric 
By using this equation:
a(n)=a*r^(n-1)
and we have <u>a=80 , r=9/10</u>
Then       <u>a(n)=80*(9/10)^(n-1)</u>
<em>I really hope this helps <3</em>
 
        
             
        
        
        
Answer:
r = i + j + (-2/3)(3i - j)
Step-by-step explanation:
Vector Equation of a line - r = a + kb ; where r  is the resultant vector of adding vector a and vector b and k is a constant
if a = i + j ; b = t(3i - j) and r = -i +s(j)
for this to be true all the vector components must be equal
summing i 's
i + 3ti  = -i; then t = -2/3
j - tj = sj; then s = 1-t; substitue t; s=1+2/3 = 5/3
so r = i + j + (-2/3)(3i - j) which will symplify to -i + 5/3j
 
        
             
        
        
        
Answer:
x=-1
Step-by-step explanation:
 
        
                    
             
        
        
        
Change into improper fraction 
take 3 x 25+18 divided by 25=93\25
93\25=3.72
        
             
        
        
        
D.  11,475  (135/200= .675 =67.5 %) (67.5% x 17,000 = 11,475)