Question

$\frac{50}{ {x}^{2} } - \frac{ {2x}^{2} }{81} \: \\ \\ factorise \: the \: above$

Answer 1

Given 50/x^2 - 2x^2/81
  
         = 50 * 81 - (2x^2 - x^2)/81x^2

         = 4050 - 2x^4/81x^2


Note:      4050 - 2x^4 can be written as -2(x^4 -2025)

                                                                   -2(x^2+45)*(x^2-45).


  So, 50/x^2 - 2x^2/81 = -2(x^2 + 45) * (x^2 -45)/81x^2.


 Hope this helps!