Author Topic: Maths question  (Read 668 times)

road-runner

  • is in Slovakia.
Maths question
« on: September 18, 2019, 09:04:35 pm »
I have a formula but I cannot remember whether I multiply everything in the brackets by C then that answer to the power of 0.5 or the other way round, the brackets to the power of 0.5 and then multiply that by C. Help!

f0 = C [ (m1 + m2) / (m1 x m2 x d)]^0.5

Re: Maths question
« Reply #1 on: September 18, 2019, 09:15:18 pm »
Powers are evaluated before multiplication, in the absence of controlling brackets

Re: Maths question
« Reply #2 on: September 18, 2019, 09:15:52 pm »
sqrt first, multiply later.

Think of it like the generic quadratic formula: ax2+bx+c

BODMAS:

"Yes please" said Squirrel "biscuits are our favourite things."

T42

  • Tea tank
Re: Maths question
« Reply #3 on: September 19, 2019, 08:41:46 am »
Funny: after >50 years mucking about with computers I have operator-precedence engraved on my heart, but when I saw that BODMAS thing in an FB post I couldn't work out where the O came from. Exponentiation & Power don't hack it.
I've dusted all those old bottles and set them up straight.

Kim

  • Timelord
Re: Maths question
« Reply #4 on: September 19, 2019, 01:14:32 pm »
Funny: after >50 years mucking about with computers I have operator-precedence engraved on my heart, but when I saw that BODMAS thing in an FB post I couldn't work out where the O came from. Exponentiation & Power don't hack it.

When I was taught it as a scrawny second-year, the 'O' stood for "pOwers Of".  This appeared to be irritatingly memorable.

I expect kids today are singing it to the tune of Humpty Dumpty or something.
To ride the Windcheetah, first, you must embrace the cantilever...

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Maths question
« Reply #5 on: September 19, 2019, 01:18:01 pm »
I was taught BEDMAS with the E standing for Exponents, or was it Equations?
sideways bounding monkey lounging under fruit tree

Re: Maths question
« Reply #6 on: September 19, 2019, 01:24:13 pm »
Exponents.

BEDMAS / BODMAS / PEDMAS / PODMAS are all the same.

Brackets / Parentheses
Orders / Exponents
...
"Yes please" said Squirrel "biscuits are our favourite things."

Re: Maths question
« Reply #7 on: September 19, 2019, 01:50:01 pm »
BIDMAS (I=Indices)

Re: Maths question
« Reply #8 on: September 20, 2019, 04:59:10 pm »
I was taught it as "O=over", i.e. come before.

T42

  • Tea tank
Re: Maths question
« Reply #9 on: September 20, 2019, 05:15:30 pm »
Nuther one: take the expression  a(b+c)

In NI I we would say this as "a upon b+c", but when I went to Scotland they said it as "a into b+c".  For me, into meant divide, so that meant (b+c)/a, whereas for them "a upon b+c" meant a/(b+c); although more commonly we would both use "over" for divided by.

My first term in Edinburgh was a wee bit hairy at times.
I've dusted all those old bottles and set them up straight.

Kim

  • Timelord
Re: Maths question
« Reply #10 on: September 20, 2019, 05:33:43 pm »
Nuther one: take the expression  a(b+c)

It's been an eternity since I did maths out loud, but if I had to pronounce it I'd either read out the brakcets, or say "a times b-plus-c", hoping to convey the precedence with speed and intonation[1].


Quote
In NI I we would say this as "a upon b+c", but when I went to Scotland they said it as "a into b+c".  For me, into meant divide, so that meant (b+c)/a, whereas for them "a upon b+c" meant a/(b+c); although more commonly we would both use "over" for divided by.

My first term in Edinburgh was a wee bit hairy at times.

Driving lessons in the People's Republic of South Yorkshire were interesting.  "Stop in this lane here" he said...



[1] Inspired by a lecturer getting into a muddle about how to pronounce the serifs, I've also been known to say "class" and "clarse" to differentiate class and Class in OO programming.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Maths question
« Reply #11 on: September 20, 2019, 07:12:12 pm »
Nuther one: take the expression  a(b+c)

a open paren b plus c close paren

or

a times brackets b plus c
"Yes please" said Squirrel "biscuits are our favourite things."

Kim

  • Timelord
Re: Maths question
« Reply #12 on: September 20, 2019, 10:26:37 pm »
In school maths we were taught that these () are brackets and these [] are square brackets. 40 years after leaving school I learned that these () are parentheses and these [] are brackets.

It's one of those USAnian vs Commonwealth English distinctions.  I grew up with adults saying one thing and computer manuals saying another, and soon got the hang of it.  A bit like code switching expletives, really.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: Maths question
« Reply #13 on: September 20, 2019, 10:57:22 pm »
Nuther one: take the expression  a(b+c)

In NI I we would say this as "a upon b+c", but when I went to Scotland they said it as "a into b+c".  For me, into meant divide, so that meant (b+c)/a, whereas for them "a upon b+c" meant a/(b+c); although more commonly we would both use "over" for divided by.

My first term in Edinburgh was a wee bit hairy at times.

Another vote for "into".  Yes, I'm Scottish, too, but I also recall that use on my engineering degree course at an English university.

Re: Maths question
« Reply #14 on: September 20, 2019, 11:19:10 pm »
Now you know why most maths gets written down :P

Cudzoziemiec

  • Solar powered, tea fuelled cycle-wol
Re: Maths question
« Reply #15 on: September 22, 2019, 11:48:32 am »
Nuther one: take the expression  a(b+c)

In NI I we would say this as "a upon b+c", but when I went to Scotland they said it as "a into b+c".  For me, into meant divide, so that meant (b+c)/a, whereas for them "a upon b+c" meant a/(b+c); although more commonly we would both use "over" for divided by.

My first term in Edinburgh was a wee bit hairy at times.
For me, into and over would both mean divide but in opposite directions. "a into b" would mean b/a, whereas "a over b" would mean a/b. But I'm not a mathematician.
sideways bounding monkey lounging under fruit tree