Discussion about math, puzzles, games and fun. Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ π -¹ ² ³ °

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Obviously, you want 1/2 of 3/4 of old fashioned oats for making 1/2 of the recipe. Maybe what it isn't so obvious is that division by 2 gives the same result as multiplication by 1/2:

To make sense of the above, remember that any number can be rewritten as the number over 1...

...and to get half of *something*, we have to divide it by 2...

...which can be rewritten as a multiplication...

And so...

Bob, that is a very clear explanation. Thanks for taking the time.

**numquester**- Replies: 2

I came across a video in which the author explains visually how to arrive at the quadratic formula, except he skips some steps.

Here is the video: https://www.youtube.com/watch?v=EBbtoFMJvFc

I follow it up to this point, where some steps are skipped: https://www.youtube.com/watch?v=EBbtoFMJvFc&t=7m45s

In the video, the right side of the equation goes from:

To:

So I think that I can rewrite the first example like this:

But I don't see how the ** a** can be moved to the numerator. Or maybe I'm approaching it all wrong.

By the way, I really like this approach to explaining math. I never understood what 'completeing the square' actually means until I saw this video. It seems right at home with so many of the nice explanations here at Math is Fun.

Side note: I really appreciate the LaTeX integration in the forum. This is nice!

Agnishom wrote:

I like writing too. Have you seen my notes?

They could be hidng in a piano, or other such place.

Agnishom wrote:

Ghoulash?

A main ingredient in ghoul gravy, which gained popularity shortly after the development of the modern crematory.

**numquester**- Replies: 66

I assume that it is an abbreviation for, <something> math.

Thanks.

**numquester**- Replies: 3

I'm relearning algebra after some years of being away from school, and I'm learning to use Geogrebra. At the moment I'm plotting some lines to get a sense of what elementary functions look like on a grid. I never really got a good sense of this when I was in school.

So I have:

f(x) = x , which gives a diaganol line.

f(x) = -x , which gives a mirror of the above diagonal line (Is there a math term for this?).

f(x) = 0x , which gives a horizontal line.

How would I plot a vertical line? The closest that I have found is:

f(x) = 10^(100)x

**numquester**- Replies: 3

Great site. I have been visiting here sporadically over a couple of years, and it is always a good experience. I guess it is about time that I joined the forum. Thanks to everyone who contributes to the site and discussion on the forum.

About myself: I am an adult who never learned much math outside of basic algebra. I am going back and relearning algebra, looking at going much further. My interests in math stem from interests in music, electronics, programming, carpentry, and other areas. And I am coming around to finding out that math is interesting in it's own right.

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