(-8x^4)(5x^9) Use the product rule to simplify.?

(-8x^4)(5x^9) = -40x^13.

According to the Product Rule for Exponents, when you have two power with the same base, the product of powers is the sum of the exponents.

(-8x^2)(5x^9)
= (-8)(5)(x^2)(x^9)
= (-40)[x^(2 + 9)]
= (-40)[x^11]
= -40x^11

answer is -40x^13

(-8x^4)(5x^9) = -8*5(x)^(4+9) = -40x^13