h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I honestly don't know whether to laugh or cry:

I was at this game forum I frequent (hey, I'm a gamer geek), and one of our regulars posted his homework in the off-topic forum, asking for help. It was the formula for a curve; he wanted to know the x and y values and turning point: y= -2x² -7x+5.

And this guy who replied to that post wrote, and I QUOTE:

-----------------------------------------------------------------------
X = 5/3

and Y = 5

That is, if I'm not completely retarded, which I probably am. You've gotta substitue 0's in the Y spot, to solve for X, or in the X spot to solve for Y.

Doing shit like centriods currently in math, lucky for you it entails alot of (X, Y).

X-

Y = -2x2 -7x+5

0 = 4x-7x+5
0 = -3x+5
3x = 5
x = 5/3

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!!!!!!!

Since when was it taught in school that 2x²=4x? [buries head in hands]

Anyway, after setting the guy straight, I worked out the values of x as 0.6085 and -4.1085 (to 4 decimal places) using the quadratic formula. Because I'm never confident of my answers even when I know I'm right, I got Ham to do it as well... and I got the second shock of the day when he told me I was dead wrong, and that x was 2.5 and 1. Which, when I replaced the values in the formula, didn't make sense. The whole thing utterly deflated me... until I realised that he'd mistaken the formula for 2x² -7x+5! whereupon he arrived at the same answers as I did.

But anyway.... 2x²=4x!!!! I despair at the modern American education system.

Hmm... has someone been learning differentiation, and got confused..? From my dim and distant murky past, I seem to remember that if y = 2x² then dy/dx = 4x

Fortunately, I don't have to worry about maths any more, although as of next week, I start tutoring a friend's daughter (and her friend) in A-level Biology (which should be OK, apart from the plant stuff) and Chemistry

Differentiation gone wrong was my first thought about the 4x mistake too.

Ok... So... A friend has a kid about 9 or 10 years old. She asks me to look at his homework to see if it makes any sense. Problem three:

"What is the factor family of 7, 8, 15?"

....


...

WTF if a "factor family"?

OMG they've got newer new math!




My personal hero is Richard Feynman. He was given a position on the board that choses the text books for the state of California. What he didn't realise at the time was that it was largely an honorary position and that the other members did not personally read the text books they were given to accept or decline. That task was usually given to assistants who would present the board members with synopses. Dr. Feynman actually read the books cover to cover. When he looked at the maths book he came across something called "Set Theory". I remember learning set theory when I was in school. I remember the symbols for the union and intersection of sets and the symbol for a null set... all that carp. Richard Feynman asked the other board members to give an example of ANYONE who would actually need to learn set theory to do their job. He wanted to know why ANYONE would ever need to learn that. They couldn't find any real world application of set theory but they thought they needed to teach it to kids anyway.


I still don't know what a "factor family" is.

Bayes theorem, which is used quite a bit in things like medicine (by the sort of people who think, rather than the ones who poke patients and dish out drugs) is really just a very basic bit of set theory given a posh name. So yes, it gets used. I use it.

I can't help you with your even newer new math though. I never did like the silly names, eg the above one which is merely pretending to be something new. A factor family should be the family of a factor (ie agent/official).