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What are the first 4 terms of f(n-1)+15

If f(1) = 7

 Jan 8, 2016

Best Answer 

 #2
avatar+26367 
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What are the first 4 terms of f(n-1)+15

If f(1) = 7

 

 

 

\(\begin{array}{rcll} f(2) &=& f(2-1)+15 \\ f(2) &=& f(1)+15 \qquad | \qquad f(1) = 7\\ f(2) &=& 7+15\\ f(2) &=& 22 \\\\ f(3) &=& f(3-1)+15 \\ f(3) &=& f(2)+15 \qquad | \qquad f(2) = 22\\ f(3) &=& 22+15\\ f(3) &=& 37 \\\\ f(4) &=& f(4-1)+15 \\ f(4) &=& f(3)+15 \qquad | \qquad f(3) = 37\\ f(4) &=& 37+15\\ f(4) &=& 52 \\\\ \cdots \end{array}\)

 

 

arithmetic sequence: \(\boxed{ ~ a_n=a_1+(n-1)\cdot d ~}\)

 

\(\begin{array}{rcll} f(n) &=& f(n-1)+15 \\ f(n)- f(n-1) &=& 15 \\ d &=& 15\\\\ \end{array}\)

 

\(\begin{array}{rcll} a_1 = f(1) &=& 7 \\ d &=& 15 \\\\ a_n &=& 7 + (n-1)\cdot 15 \\ a_n &=& 7 + 15n -15 \\ \mathbf{ a_n} & \mathbf{ = } & \mathbf{ -8 + 15n } \end{array}\)

 

laugh

 Jan 8, 2016
 #1
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  If f(1) = 7, what are the first 4 terms of f(n-1)+15

 

7,  21, 35, 49, 63, 77...........

 Jan 8, 2016
 #2
avatar+26367 
+10
Best Answer

What are the first 4 terms of f(n-1)+15

If f(1) = 7

 

 

 

\(\begin{array}{rcll} f(2) &=& f(2-1)+15 \\ f(2) &=& f(1)+15 \qquad | \qquad f(1) = 7\\ f(2) &=& 7+15\\ f(2) &=& 22 \\\\ f(3) &=& f(3-1)+15 \\ f(3) &=& f(2)+15 \qquad | \qquad f(2) = 22\\ f(3) &=& 22+15\\ f(3) &=& 37 \\\\ f(4) &=& f(4-1)+15 \\ f(4) &=& f(3)+15 \qquad | \qquad f(3) = 37\\ f(4) &=& 37+15\\ f(4) &=& 52 \\\\ \cdots \end{array}\)

 

 

arithmetic sequence: \(\boxed{ ~ a_n=a_1+(n-1)\cdot d ~}\)

 

\(\begin{array}{rcll} f(n) &=& f(n-1)+15 \\ f(n)- f(n-1) &=& 15 \\ d &=& 15\\\\ \end{array}\)

 

\(\begin{array}{rcll} a_1 = f(1) &=& 7 \\ d &=& 15 \\\\ a_n &=& 7 + (n-1)\cdot 15 \\ a_n &=& 7 + 15n -15 \\ \mathbf{ a_n} & \mathbf{ = } & \mathbf{ -8 + 15n } \end{array}\)

 

laugh

heureka Jan 8, 2016

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