Question

Алгебра. проверь себя. 1,2,3.

Answer 1

1) (a+3)^2 + (a-3)(a+3) + 6a = a^2 + 6a + 9 + a^2 - 3^2 +6a = 2a^2 + 12a

2) xy-2y=y(x-2)
 16a^2 - 81 = 4^2a^2 - 9^2 = (4a-9)(4a+9)
  3x^2 - 6x^3 = 3x^2(1-2x)
  x^2-10x+25 = (x-5)^2
  3(x-1) +y(x-1) = (x-1)(3+y)
  2a^2 - 4ab + 2b^2 = 2(a-b)^2

3)  a^2 - 3ab + 3a - 9b = a(a+3) - 3b(a+3) = (a+3)(a-3b)  = (1 + 3)*[1-3*(-1/3)]=

   = 4*[1 + 1] =8