Question

Factorise (a²- 2a)² - 23(a² - 2s) + 120

Answer 1

Answer:

     (a²- 2a)² - 23(a² - 2s) + 120

  Let (a²- 2a) be x

Now,

         x² -23x+120

       =x² -(15+8)x+120

       =x² -15x-8x+120

       =x(x-15)-8(x-15)

       =(x-15) (x-8)........................1)

Again,

Substituting value of x in 1)

         (x-15) (x-8)

       =(a²- 2a-15) (a²- 2a-8)

       ={a²-(5-3)a-15} {a²-(4-2)a-8}

       =(a²-5a+3a-15) (a²-4a+2a-8)

       ={a(a-5)+3(a-5)} {a(a-4)+2(a-4)}

       =(a-5) (a+3) (a-4) (a+2)