(a-2)^2= (a-3)(a+3)= (x-1)(x^2+x+1)

1 ) ( a - 2 ) ^ 2 = a ^ 2 - 2 * a * 2 + 2 ^ 2 = a ^ 2 - 4 * a + 4 ; 2 ) ( a - 3 ) * ( a + 3 ) = a * a + 3 * a - 3 * a - 3 * 3 = a ^ 2 + 3 * a - 3 * a - 9 = a ^ 2 - 9 ; 3 ) ( x - 1 ) * ( x ^ 2 + x + 1 ) = x * x ^ 2 + x * x + 1 * x - 1 * x ^ 2 - 1 * x - 1 * 1 = x ^ 3 + x ^ 2 + x - x ^ 2 - x - 1 = x ^ 3 - 1.