There's a variable f = expression("2t+5") and it's used in a mathematical expression part's expected answer field: t*({f}).
The resulting correct answer is 2t*t + 5. It looks like the brackets around f are lost, so the substitution produces t*2t + 5, and then it's rearranged.
The substitution is performed correctly when done in a variable definition, f2 = expression("t*({f})"), but not when the brackets around {f} are omitted. That also needs to be fixed.
Example by Martin Jones: https://numbas.mathcentre.ac.uk/question/142459/error-multiplying-functions/
There's a variable
f = expression("2t+5")and it's used in a mathematical expression part's expected answer field:t*({f}).The resulting correct answer is
2t*t + 5. It looks like the brackets aroundfare lost, so the substitution producest*2t + 5, and then it's rearranged.The substitution is performed correctly when done in a variable definition,
f2 = expression("t*({f})"), but not when the brackets around{f}are omitted. That also needs to be fixed.