## WeBWorK Problems

### General Solution - Vector Parametric Equation ### General Solution - Vector Parametric Equation

by Marie-Claude Bonneau -
Number of replies: 2

Hello,

I wanted to make sure students could enter the general solution of a system of linear equations as a vector form without the actual standard vector format. So, I modified the following problem  /Library/Rochester/setLinearAlgebra1Systems/ur_la_1_14.pg  using https://webwork.maa.org/wiki/VectorParametricLines as a guide. The problem is that WeBWorK recognizes (21,-14,t)+t(22,-17,0) as equivalent to (21,14,0)+t(22,17,1)

Is there a way of having WeBWorK recognize that (21,-14,t)+t(22,-17,0) is incorrect?

Enclosed is the relevant portion of the modified code.

Thank you.

Marie-Claude ### Re: General Solution - Vector Parametric Equation

by Danny Glin -
It is by design that WeBWorK recognizes (21,-14,t)+t(22,-17,0) as correct, since it is mathematically equivalent to (21,−14,0)+t(22,−17,1). The goal with WeBWorK answer checkers is to accept any correct answer.

I think that it will be very hard to write an answer checker that accepts (21,−14,0)+t(22,−17,1) but not (21,-14,t)+t(22,-17,0). If you want to force the students to enter an answer in a specific format, you would need to write heuristics that determine what is acceptable. For example, should t(22,−17,1)+(21,-14,0) be marked correct? In fact, the original question you quoted does a good job of forcing the student to separate the constant, and it also allows for different parameterizations, so I'm not sure what you are trying to accomplish. 