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Secondary 1 | Maths
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Is my Qn 3 & 4 correct? Thanks
You only multiply the 4 once, not twice.
This is not distributive law
i.e it is not 4(-2 + 3) = 4(-2) + 4(3)
= √(25 - 4(-6))
= √(25 - (-24)
= √(25 + 24)
= √49
= 7
x = √(5² - 4(-2×3))
= √(25 - 4 × (-2) × 3)
= √(25 - (-8) × 3)
= √(25 - (-24))
= √(25 + 24)
= √49
= 7
Two mistakes :
①Andy only improved by 10 percentage points in Test 2 but his father misinterpreted's Test 2's result as twice of Test 1's because he saw that the area of the bar is twice of Test 1's.
② Besides, even if Andy's Test 2 score were indeed twice of Test 1's, it should be phrased as 'improved by one time' and not' by two times'. The increase/improvement is not two times of Test 1 score but only equal to it.
ac or xy or gh or 5y or 9c , etc are all products (multiply)
you don't necessarily have to multiply inside the brackets first.
The second working for 4ac shows this :
4 × (-2) × 3
It can also be written as
4(-2)(3)
Instead of using a bar chart, Andy should use a line graph instead.
This avoids the misinterpretation of the diagram as an area-specific one since lines are taken to be 1 dimensional and have no thickness(which in turn means no area)
See 1 Answer
A 60% point vs 70% point bar would just lead his dad to think it is a improvement of 1/6 times but for such tests that are scored out of 100% we should be thinking in terms of % points instead.
I.e a 10% point improvement.
Thinking in terms of the number of times does not quite demonstrate improvement well.
Eg. If I score 3% points for test 1 and 30% points for test 2, I have improved by 9 times by this perspective, and that phrase '9 times' seems like a lot.
But actually, it is only a 27% point increase , which is rather insignificant since I still failed (assuming the passing mark is 50%)