Checking for careless mistakes using the Substitution Method
- Normal method of checking (i.e. check your working from front to back again), may or may not find the error
- Using Substitution Method of checking guarantees that your answer is correct, and will find an error if there is one.
- Use Substitution Method of checking for all algebra/solving/simplify questions worth 2 marks or more. You will be able to save many many marks using this method!
- Only takes 10 seconds with practice. (use calculator)
Example (using substitution method)
Express as a single fraction in its simplest form. [2 marks]
After getting your answer (), you can substitute in the value .
When, , , and
Since both expressions give the same value, you have just checked that your answer is correct!