Sn=[2a(n-1)d]

Solution for Sn=[2a(n-1)d] equation:

Simplifying
Sn = [2a(n + -1) * d]

Reorder the terms:
nS = [2a(-1 + n) * d]

Reorder the terms for easier multiplication:
nS = [2a * d(-1 + n)]

Multiply a * d
nS = [2ad(-1 + n)]
nS = [(-1 * 2ad + n * 2ad)]
nS = [(-2ad + 2adn)]
nS = [-2ad + 2adn]

Remove brackets around [-2ad + 2adn]
nS = -2ad + 2adn

Solving
nS = -2ad + 2adn

Solving for variable 'n'.

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

Add '-2adn' to each side of the equation.
-2adn + nS = -2ad + 2adn + -2adn

Combine like terms: 2adn + -2adn = 0
-2adn + nS = -2ad + 0
-2adn + nS = -2ad

Reorder the terms:
2ad + -2adn + nS = -2ad + 2ad

Combine like terms: -2ad + 2ad = 0
2ad + -2adn + nS = 0

The solution to this equation could not be determined.