Question 298930
*[invoke describe_linear_equation 4, 2, 8 ]*[invoke substitution "x^2-2x", "x", 3 ]
*[invoke explain_simplification "x+x-x+2x=6" ]

*[invoke substitution "x^2-2x", "x", 3 ]
*[invoke linear "x", "y", 1, 1, 2, 1, -1, 0 ]