Saturday, February 23, 2013

The sound of my inner nerd rolling around in slippery numerical joy

Ok. Time for me to explain and solve the algebra thing I posted a couple days ago.

It really is easy.
I swear.

First, let's look at the top one.

30xy = x squared.

Divide both sides by x and you see that 30y=x.

Save that for a little later.  Let's move on to the second one.
(x+y) over two equals 31.
Multiply both sides by two and you see that x+y = 62.

Since we already know from the top problem that 30y=x, just substitute 30y for x in the second problem.

So instead of x+y=62, it's (30y)+y = 62.

30y plus another y is the same thing as saying 31y, so it's 31y=62.

Thus, y = 2.

Now that we know what y is, go back to the first problem and plug it in.

30y = x

30 times 2 = x.

Therefore, x = 60.

We didn't even need the third problem!

But both numbers fit there too.  Here, let's solve it anyway.

The square root of x+y+2 is 8.

Square both sides and you find that the actual value of x+y+2 is 64.

Subtract two from both sides and you see that x+y = 62.

And you can plug in either value from the first two problems.

60+2=62.


See how much fun this is?
Isn't this great?
And I made all three of these up just to entertain myself.

Guys?
Is anyone there?

Hello?

Anyone?


12 comments:

nonamedufus said...

Man, that pizza was good.

Grace said...

Yeah - No...

Janna said...

nonamedufus: You saved some for me, didn't you? ....Didn't you?

Grace: But it's easy!

Shelly said...

I actually enjoyed algebra in high school. I never needed to use it since. Until now. I'd forgotten everything about solving vacations, and now you've brought it back. Damn you. ;)

Janna said...

Shelly: Vacations are easy to solve. Sometimes equations are too. :) LOL. I'm glad it brought back memories. :)

Shelly said...

Good grief. I didn't even notice I'd typed that. Holy Freudian Slip, Batman! ;)

nonamedufus said...

I saved you x pieces. Y, I don't know.

Janna said...

Shelly: If I remember correctly, a Freudian slip has to have sexual undertones. So you could have said "I'd forgotten everything about solving erections, but..."

nonamedufus: Since X=60, that's a lot of pizza! Thank you.

Shelly said...

LOL. A Freudian slip can be anything that reveals what you're really thinking. Which for most people tends to be about sex. ;)

G-Man said...

Janna....
All this crap seems like secret agent spy code stuff. Thank you for giving me a headache.
I'll get even.....Some Day!

Rastaman said...

This is SO interesting!

Janna said...

Shelly: And, in your case, apparently it's about vacations!

G-Man: Just wait til you see my car with the bullet-proof windshield and the ejector seat.

Rastaman: I hope so! :)