Question

find ( 2x - 3y + 4z ) ( 2x + 3y + 4z )

Answer 1

Answer:

3y/2x=4z/3y

=>3yz/8xz=1

=>8xz=9y2-------  (i)

L.H.S=4x2+9y2+16z2

        =4x2+8xz+16z2 (from i)

        =(2x)2+2(2x)(4z)+(4z)2−8xz

        =(2x+4z)2−9y2

        =(2x+4z)2−(3y)2

Using,a2−b2=(a+b)(a−b)

        =(2x+3y+4z)(2x−3y+4z) 

     =R.H.S