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{[f(1)=0],[f(n)=f(n-1)+2]:}
Find an explicit formula for 
f(n).

f(n)=

{f(1)=0f(n)=f(n1)+2 \left\{\begin{array}{l} f(1)=0 \\ f(n)=f(n-1)+2 \end{array}\right. \newlineFind an explicit formula for f(n) f(n) .\newlinef(n)= f(n)=

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Q. {f(1)=0f(n)=f(n1)+2 \left\{\begin{array}{l} f(1)=0 \\ f(n)=f(n-1)+2 \end{array}\right. \newlineFind an explicit formula for f(n) f(n) .\newlinef(n)= f(n)=
  1. Given Base Case and Recursive Formula: We are given the base case f(1)=0f(1) = 0 and the recursive formula f(n)=f(n1)+2f(n) = f(n-1) + 2. To find an explicit formula, we need to see how the function behaves as nn increases.
  2. Calculate First Few Values: Let's calculate the first few values of the function to identify a pattern:\newlinef(1)=0f(1) = 0 (given)\newlinef(2)=f(1)+2=0+2=2f(2) = f(1) + 2 = 0 + 2 = 2\newlinef(3)=f(2)+2=2+2=4f(3) = f(2) + 2 = 2 + 2 = 4\newlinef(4)=f(3)+2=4+2=6f(4) = f(3) + 2 = 4 + 2 = 6\newlineWe can see that each time nn increases by 11, the function value increases by 22.
  3. Identify Pattern: From the pattern, we can infer that f(n)f(n) increases by 22 for each increment in nn starting from f(1)f(1). So, we can express f(n)f(n) as 22 times the number of increments from 11 to nn. Since f(1)=0f(1) = 0, the number of increments from 11 to nn is 2211.
  4. Infer Increment Relationship: Therefore, the explicit formula for f(n)f(n) is f(n)=2×(n1)f(n) = 2 \times (n - 1).
  5. Verify Formula: Let's verify the formula with the base case and one other value:\newlineFor n=1n = 1, f(1)=2×(11)=2×0=0f(1) = 2 \times (1 - 1) = 2 \times 0 = 0, which matches the given base case.\newlineFor n=3n = 3, f(3)=2×(31)=2×2=4f(3) = 2 \times (3 - 1) = 2 \times 2 = 4, which matches the value we calculated earlier.

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