Know the important mathematical properties of direct proportion!
Didn't we see yesterday
that all equivalent fractions are direct proportional!
Let us tabulate equivalent
fractions of ¼ as numerator and denominator as follows?
Numerator |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
Denominator |
4 |
8 |
12 |
16 |
20 |
24 |
28 |
32 |
36 |
40 |
Looking at the above
table, what do you think?
Look from left to
right. That is, look from here to there. Numerators go incrementally. Not only
numerators? Denominators are also increasing.
Now look from right to
left. I mean look from there to here. Numerators go lower. Not only numerators?
Denominators also go low in values.
Now consider one more
thing. As the numerator increases, the denominator also increases, doesn't it?
Or if the numerator decreases when viewed from right to left, the denominator
also decreases accordingly!
It is this mathematical
property that you should observe.
As the numerator
increases the denominator also increases. As the numerator decreases, the
denominator also decreases. This is the mathematical property of direct proportionality.
If it increases, both the elements numerator and denominator will increase. If
it decreases, both elements, the numerator and denominator, will decrease.
And if the opposite
happens, should I say what it is? That is the inverse proportion. That means
numerator decreases as denominator increases or numerator decreases as
denominator increases.
I think you understand
better now.
Let's focus on the
multiplication tables anyway shall we? If so, what we saw above is the fourth
table? Are the numbers that are multiplied by the order of four in the
numerator and the product that is multiplication value in denominator?
Is that all? In terms
of geometry and measurements, all that is numerator is the sides of a square.
Aren't all denominators the perimeters of a square with corresponding sides?
See where we start and
where we end up. See how each of the math topics relate to each other.
Now you should know an
important mathematical property of equivalent fractions.
Take any two equal
fractions from the above table and equate them.
For example
2 / 8 = 3 / 12
Let's simplify both of
these on both sides.
Does dividing the
fraction on the left up and down by 2 and come to ¼?
Similarly, if the
fraction on the right is rounded up and down by three i.e. divided, does it
come to ¼?
Not only these two
equivalent fractions are equal, but if we take the other equivalent fractions
in the table and simplify them, we get ¼.
Thus, no matter how you
simplify equivalent fractions, they will return to their simplest form. Do I
need to tell you how we can represent this with variables? Does x / y = a constant?
This is an important
mathematical property of equivalent fractions. An important mathematical
property not only for equivalent fractions but also for direct proportion.
Also cross multiply the
equal fractions 2 / 8 = 3 / 12 that we equated above. That is, multiply the
numerator of the fraction on the right by the denominator of the fraction on the
left. Similarly, multiply the numerator of the fraction on the right by the
denominator of the fraction on the left. Equate the two multiplied products.
Equally means,
2 × 12 = 3 × 8
Does 24 = 24 come up?
Similarly, if we take
any two equal fractions mentioned in the table and do cross multiplication, we
get the same answer on both sides of the equation.
This is also an
important mathematical property of equivalent fractions. It is also an
important mathematical property for direct proportion. It is by using this
property that we are going to easily find the answer to proportionality
calculations. So remember this mathematical property well.
I told you that today I
will tell you about the application of proportionality in life. But look, I've
said a lot, so I'll say it tomorrow!
Wait a day. Let us know
the life application of direct proportion tomorrow.
Before that, let's
summarize and remember the important concepts we have learned in direct
proportion.
1. If one element
increases in direct proportion, the other element also increases. Or if one
element decreases, the other element also decreases.
2. Taking and reducing
any ratio of a direct proportion gives a constant.
3. If two ratios of a
direct proportion are cross-multiplied, the products obtained are equal.
What we compiled is
correct? Remember this well. We will see about the rest tomorrow.
*****
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