Question

Factorise the 4x square _y square/25

Answer 1

4x² - (y²/25) = (2x)² - (y/5)²

                   = [2x - (y/5)}[2x + (y/5)]           [ using a²-b² = (a+b)(a-b) ]

                  = (10x-y)(10x+y)/25