1.1 Solve for x: 1.1.1 …
This has 2 marks, and 2 marks is 2 minutes of work maximum. However, you can solve this far quicker since you have already been given everything you need to know in the question.
You will recognise this as a factored quadratic expression,, and thus you do not need to do the factoring first.
For any expression of the form to equal zero() it is required that either one of or is equal to zero. It is not possible for this expression to be zero is both are non-zero, and thus one MUST be zero, and this means that EITHER or BOTH can be zero for the expression to be zero.
Thus we can divide this up into two expressions:
Similarly for the other expression
From we can determine that .
NOTE: This is and not (which would be considered a silly mistake).
When writing this answer consider that the examiner is expecting to see, which parts of your answer have value which would warrant the allocation of a mark.
1 MARK: Giving the information that EITHER of the parts must be zero.
1 MARK: Giving the correct answer.
How you write this answer is important, to emphasise to the examiner where your most important parts of your answer are, even if you have done other calculations.
TRY THESE EXAMPLES YOURSELF: