r=(w-9)(w+9)

Solution for r=(w-9)(w+9) equation:

Simplifying
r = (w + -9)(w + 9)

Reorder the terms:
r = (-9 + w)(w + 9)

Reorder the terms:
r = (-9 + w)(9 + w)

Multiply (-9 + w) * (9 + w)
r = (-9(9 + w) + w(9 + w))
r = ((9 * -9 + w * -9) + w(9 + w))
r = ((-81 + -9w) + w(9 + w))
r = (-81 + -9w + (9 * w + w * w))
r = (-81 + -9w + (9w + w2))

Combine like terms: -9w + 9w = 0
r = (-81 + 0 + w2)
r = (-81 + w2)

Solving
r = -81 + w2

Solving for variable 'r'.

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

Simplifying
r = -81 + w2