f(n+1)=f(n)+2n

Solution for f(n+1)=f(n)+2n equation:

Simplifying
f(n + 1) = f(n) + 2n

Reorder the terms:
f(1 + n) = f(n) + 2n
(1 * f + n * f) = f(n) + 2n
(1f + fn) = f(n) + 2n

Multiply f * n
1f + fn = fn + 2n

Add '-1fn' to each side of the equation.
1f + fn + -1fn = fn + -1fn + 2n

Combine like terms: fn + -1fn = 0
1f + 0 = fn + -1fn + 2n
1f = fn + -1fn + 2n

Combine like terms: fn + -1fn = 0
1f = 0 + 2n
1f = 2n

Solving
1f = 2n

Solving for variable 'f'.

Move all terms containing f to the left, all other terms to the right.

Divide each side by '1'.
f = 2n

Simplifying
f = 2n