Factorise: 16x5 - 144x3
explanation..... see, here it's 16x5 - 144x3, so in these terms, 16 and x3 are common.
See this, you will understand, (2*2*2*2*x*x*x*x*x) - (2*2*2*2*3*3*x*x*x)
So the common among the two terms are 2*2*2*2*x*x*x = 16x3
Now, when you take16x3 as common, it will become like this,
16x3 (x2 - 9)
See, above this is given in the bracket (x2-9), for a while, forget about 16x3
You can also write it as (x2-32), right?
So, this matches with the identity, a2 - b2 = (a+b) (a-b)
Thus, (x2 - 32) which will be equal to (x+3) (x-3)
So, thus the factorised number will be 16x3 (x+3) (x-3)
Hope, you understood....
Well, is your book is of RS Agarwal ?