Answer: -3y^3z^6(5y^4+z^2)
Explanation: The first number in the parenthesis has to be positive, so the GCF in this problem will be negative. The GCF between the coefficients is 3. The GCF between the y variable is y^3. The GCF between the z variable is z^6. We combine all of the GCFs to get an overall GCF: -3y^3z^6. Then we will factor it out of the two terms, giving us: -3y^3z^6(5y^4+z^2). You can check the answer by multiplying them to see if you get the original expression.