Answer:
The error is located in step 9, because the student made the following operation: , instead of , presented in step 4) of our demonstration. The real solution is 9.
Step-by-step explanation:
First, we proceed to show the appropriate process to solve the equation for by algebraic means. That is:
1) Given
2) Definition of substraction
3) Distributive property
4) /
5) Compatibility with addition/Commutative and associative properties
6) Existence of additive inverse/Modulative property
7) Compatibility with multiplication/Commutative and associative properties
8) Existence of multiplicative inverse/Definition of division/Result
The error is located in step 9, because the student made the following operation: , instead of , presented in step 4) of our demonstration. The real solution is 9.