Math CentralQuandaries & Queries


Question from Monica, a student:

I have to factor the following two items completely, but I am lost. I've tried factoring by substitution and grouping but they don't seem to work:

1. 5(w-3z) -10(w-3z)=

2. ab-21+a3-b7=

Please help me to understand. Thank you.

Hi Monica,

In your first problem there is a common factor of (w - 3z) which gives

5(w - 3z) - 10(w - 3z) = (5 - 10)(w - 3z) = -5(w - 3z)

I don't understand your second problem. Are you sure you have stated it correctly?


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