Math CentralQuandaries & Queries


Question from Catherine, a student:


I am having a problem solving this question:

5x squared - 15x - 200

Hi Catherine,

First I see a common factor of 5. This is important because it reduces the size of the coefficients.

5x2 - 15x - 200 = 5(x2 - 3x - 40)

To factor x2 - 3x - 40 you need to find two integers whose product is 40 and difference is 3. Can you see what they are?


About Math Central


Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.
Quandaries & Queries page Home page University of Regina PIMS