Answer :
First, multiply the brackets out:
(8x^4 - x + 1)(-x^5 + 5)
= -8x^9 + x^6 - x^5 + 40x^4 - 5x + 5
Then, find f'(x) by multiplying each term by the power, then reducing the power by one:
f'(x) = -72x^8 + 6x^5 - 5x^4 + 160x^3 - 5
(8x^4 - x + 1)(-x^5 + 5)
= -8x^9 + x^6 - x^5 + 40x^4 - 5x + 5
Then, find f'(x) by multiplying each term by the power, then reducing the power by one:
f'(x) = -72x^8 + 6x^5 - 5x^4 + 160x^3 - 5
