Tuesday, April 17, 2018

algebra precalculus - Simplify a rational expression

Suppose I want to simplify this expression:

$$\frac{bx-bc-dx+ad}{a-c}$$
More specifically, I want to minimize the number of operations. Counting each addition, subtraction, and multiplication, the expression requires 9 operations to compute.



The expression $$b+\frac{(x-a)(b-d)}{a-c}$$ is equivalent to the previous expression, yet requires only 6 operations to compute.



So, my real question is, starting with the top expression, how do I derive the bottom expression? I want to know step-by-step. I can't think of any factoring techniques that would help me here. I know how to go from the bottom expression to the top expression, but not the other way around.

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