I am stuck trying to factorize the following question:
The answer in the book is
Here is my attempt to reach this answer
I recognized it now thanks to the way you laid it out. However I did not see that before because I was trying to factorize the expression by grouping the terms in pairs so that each pair of terms has a common factor.
My question is, if I did not recognize what you pointed out, how do I factorize this expression by grouping?
For example (assuming my working is correct)