what is a 4a^6b^5c^4 times -7b^7 c^6?

To multiply the two given expressions, we can multiply the numerical coefficients and add the exponents of the variables with the same base.

First, let's multiply the numerical coefficients:
4 * (-7) = -28

Next, let's multiply the variables:
a^6 * b^5 * (-7) * b^7 = -7a^6 * b^(5+7) = -7a^6b^12
b^(12) * c^4 * c^6 = b^(12+7) * c^(4+6) = b^19 * c^10

Putting it all together, we have:
-28a^6b^19c^10

wrong

Apologies for the mistake. Let's calculate it correctly:

To multiply the two expressions, we can multiply the numerical coefficients and add the exponents of the variables with the same base.

-7 * 4 = -28

For the variables:

a^6 * b^5 * b^7 = a^6 * b^(5+7) = a^6 * b^12

c^4 * c^6 = c^(4+6) = c^10

Putting it all together, we have:

-28a^6b^12c^10