Let's simplify the given expression:
(x+1)(x-1) = x^2 - 1(x+5)(x-5) = x^2 - 25-2x(x+3) = -2x^2 - 6x
Now we can simplify the expression:
(x^2 - 1) + (x^2 - 25) - (-2x^2 - 6x) + 6x^2 - 1 + x^2 - 25 + 2x^2 + 6x + 64x^2 + 6x - 20
Therefore, (x+1)(x-1) + (x+5)(x-5) - 2x(x+3) + 6 simplifies to 4x^2 + 6x - 20.
Let's simplify the given expression:
(x+1)(x-1) = x^2 - 1
(x+5)(x-5) = x^2 - 25
-2x(x+3) = -2x^2 - 6x
Now we can simplify the expression:
(x^2 - 1) + (x^2 - 25) - (-2x^2 - 6x) + 6
x^2 - 1 + x^2 - 25 + 2x^2 + 6x + 6
4x^2 + 6x - 20
Therefore, (x+1)(x-1) + (x+5)(x-5) - 2x(x+3) + 6 simplifies to 4x^2 + 6x - 20.