Question 89299

    (-6a3b4)2 
(x + 9)(x - 9) 
(3x - 7)2 
(3x + 6)(4x - 7) 
please simplify these above problems thanks bunches 



  a) (-6a^3b^4)^2 = 36 (a^3)^2 (b^4)^2
                  = 36a^6b^8

  
  b) (x+9)(x-9) = x^2-9^2 = x^2-81



  c) (3x-7)^2 = (3x)^2-2*3x*7+(7)^2
              = 9x^2 - 42x +49
 

  d) (3x+6)(4x-7) = 3x(4x-7)+6(4x-7) = 12x^2-21x+24x-42
                                     = 12x^2+3x-42