Give an example of using the distributive property for a negative monomial times a trinomial with different signs on the terms[for example:-3x(2xy+3y-2x)] and show each step of the distribution. Why do you think many students make sign errors on this type of problem? What would be your advice to a student who has trouble with signs?
Let us take example
-4y(3yz - z + x)
Use distribution property, we will get
(-4y)(3yz) -(-4y)z + (-4y)x
= -12y^2 z + ...