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version 1.3, 2005/02/15 14:59:30
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Problem Parameters'' figure. |
Problem Parameters'' figure. |
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When creating randomized problems, you want to make sure that the problems |
When creating randomized problems, you want to make sure that the problems |
always have an answer. Consider what might happen if I had chosen the two |
always have an answer. Consider what might happen if two |
slopes \emph{both} with the expression \texttt{\&random(-1.0,1.0,.2)}. One |
slopes are chosen, \emph{both} with the expression \texttt{\&random(-1.0,1.0,.2)}. One |
out of ten students would get a problem where both slopes were equal, which |
out of ten students would get a problem where both slopes were equal, which |
has either no solution (for unequal y-intercepts) or an infinite number of |
has either no solution (for unequal y-intercepts) or an infinite number of |
solutions (for equal slopes and y-intercepts). Both of these cause a division-by-zero |
solutions (for equal slopes and y-intercepts). Both of these cause a division-by-zero |
error on the division that computes the answer. There are many ways to avoid |
error on the division that computes the answer. There are many ways to avoid |
this, one of the easiest of which is picking one slope negative and one positive. |
this, one of the easiest of which is picking one slope negative and one positive. |
This same problem can show up in many other places, too, so be careful. |
This same problem can show up in many other places as well, so be careful. |