an=2(an-1+an-2)

Solution for an=2(an-1+an-2) equation:

Simplifying
an = 2(an + -1 + an + -2)

Reorder the terms:
an = 2(-1 + -2 + an + an)

Combine like terms: -1 + -2 = -3
an = 2(-3 + an + an)

Combine like terms: an + an = 2an
an = 2(-3 + 2an)
an = (-3 * 2 + 2an * 2)
an = (-6 + 4an)

Solving
an = -6 + 4an

Solving for variable 'a'.

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

Add '-4an' to each side of the equation.
an + -4an = -6 + 4an + -4an

Combine like terms: an + -4an = -3an
-3an = -6 + 4an + -4an

Combine like terms: 4an + -4an = 0
-3an = -6 + 0
-3an = -6

Divide each side by '-3n'.
a = 2n-1

Simplifying
a = 2n-1