A student attempted to check whether satisfies the equation and wrote the following…
MATHEMATICS · Multi-part · AoPS · Mathematics · One-Variable Linear Equations · One-Variable Linear Equations
Problem
A student attempted to check whether x=4 satisfies the equation 9x−4=5x+12 and wrote the following steps:
LHS =9(4)−4=36−4=32
RHS =5(4)+12=20+12=22
Therefore 32=22, so x=4 is a solution.
(i) Locate and clearly state the mathematical error in the student’s working.
(ii) Perform the verification again, correctly, to decide whether x=4 is a solution of the given equation.
(iii) Solve the equation 9x−4=5x+12 to obtain the actual solution. Verify your answer.