Hi, I don’t get these types of problems & would really like an explanation for their solution. (x- 3)(x – d) = x^2 – 2dx + m. I don’t know how to find the value of dm because I can’t isolate d without getting a fraction. Please help );

The thing to remember on a question like this is that when you have equivalent polynomials, the coefficients of each term are equal. Step 1 is to expand the left hand side.


From there, you know that the coefficients of the x^2, x, and constant terms are equal on both sides.

The x^2 coefficients are both 1, so all set there.

The coefficients of the x terms are -(d+3) and -2d, so we know -(d+3)=-2d. We can solve that for d:


The constants terms are also equal, so we know 3d=m. We already solved for d, so we can say 3(3)=-9=m.

Now substitute to find dm.


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