Expanding each term:
(x-3y)(x+3y) = x^2 - 9y^2(3y-c)(3y+c) = 9y^2 - c^2(c-x)(c+x) = c^2 - x^2
Adding all three terms together:
x^2 - 9y^2 + 9y^2 - c^2 + c^2 - x^2 = x^2 - x^2 - 9y^2 + 9y^2 + c^2 - c^2 = 0
Therefore, the equation simplifies to 0.
Expanding each term:
(x-3y)(x+3y) = x^2 - 9y^2
(3y-c)(3y+c) = 9y^2 - c^2
(c-x)(c+x) = c^2 - x^2
Adding all three terms together:
x^2 - 9y^2 + 9y^2 - c^2 + c^2 - x^2 = x^2 - x^2 - 9y^2 + 9y^2 + c^2 - c^2 = 0
Therefore, the equation simplifies to 0.