## Welcome to H3 Maths

Blog Support for Growing Mathematicians

## Archive for December, 2014

### Riding the Sine Wave…

December8

A sine wave is a repetitive change or motion which, when plotted as a graph, has the same shape as the sine function. For example, on the right is a weight suspended by a spring. As it bounces up and down, its motion, when graphed over time, is a sine wave. In reality, friction and […]

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### What do you mean by “a margin of error?”

December6

Yes, we often read about “a margin of error” when it comes to surveys or polls. Here is one that appeared in the Associated Press just the other day, regarding the upcoming elections in Israel: “JERUSALEM (AP) ” A poll conducted ahead of Israel’s March elections and published Friday indicates strong support for the country’s […]

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### Pi Day Revisited

December1

Yes, today is NOT Pi Day – well, not officially. After all, every day is Pi Day since every day Pi is being used to solve both simple and complex problems, many times without anyone realizing it. Yes, Pi might just have to be the most exciting irrational number on the planet! What do we mean […]

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### Study time for math varies widely

December1

The graph shows the % time that students study Mathematics in class. Of course this does not take into account the number of extra hours each week that students study their math.  Click on the image for a comparison for English as well:

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#### Post Support

NCEA Level 2 Algebra Problem. Using the information given, the shaded area = 9, that is:
y(y-8) = 9 –> y.y – 8y – 9 =0
–> (y-9)(y+1) = 0, therefore y = 9 (can’t have a distance of – 1 for the other solution for y)
Using the top and bottom of the rectangle,
x = (y-8)(y+2) = (9-8)(9+2) = 11
but, the left side = (x-4) = 11-4 = 7, but rhs = y+? = 9+?, which is greater than the value of the opp. side??
[I think that the left had side was a mistake and should have read (x+4)?]