Question 957361
the book is very clever.


8x * (2x+1)^3 + (2x+1)^4 is equal to:


8x * (2x+1)^3 + (2x+1)^3 * (2x+1)


factor out the common term and you get:


(2x + 1)^3 * (8x + (2x + 1))


combine like terms and you get:


(2x + 1)^3 * (10x + 1)