Answer:
He squared 4x instead of adding exponents of x and multiplying -4 by 5.
Step-by-step explanation:
When multiplying to exponents with the same base you must add the exponents. Andrew multiplied the two functions and took 4x and squared it to get 4x² which is wrong. The correct solution is:
[tex]=-4\cdot(x)\cdot(5)\cdot(x^2)[/tex]
[tex]=-20\cdot(x)^{1+2}=-20\cdot(x^3)[/tex]