Question 90864

   Simplify by combining like terms:
x Sqaure root 18- 3 square root 8x^2 
and 
simplify each radical expression 
(square root 3+5)(square root 3-3) 

   1) x.(sq rt 18)-3.(sq rt 8x^2)          (sq r 18 = sq rt 9*2  = 3.sq rt 2)
                                          
                                           (sq rt 8x^2 = sq rt x^2 sq rt 4*2
                                                       = x.2 sq rt 2)
    = x.3.sq rt 2- 3.x.2. sq rt 2
   
    = sq rt 2(3x - 6x)

    = -3x sq rt 2


   2)  (sq rt 3+5). (sq rt 3 - 3)     ( use (x+a).(x-b) = x^2+x(a-b)+ab)


        = (sq rt 3)^2+ sq rt 3 (5-3) + 5(-3)

        = 3 + 2.sq rt 3 -15