official math problem thread

Tom · Post by **Tom** » Tue Mar 25, 2008 10:16 pm

||| A | B | C ||| = (a + b + c)^(1/2)

||| 2x | 3x |4x ||| = 5x

x = ?

Yuryeong · Post by **Yuryeong** » Tue Mar 25, 2008 10:30 pm

2x + 3x + 4x = 5x
9x = 5x
x = 9/5
x = 1,8

Tom · Post by **Tom** » Tue Mar 25, 2008 10:33 pm

your first line should read:

Code: Select all

(2x+3x+4x)^(1/2) = 5x

Yuryeong · Post by **Yuryeong** » Tue Mar 25, 2008 10:36 pm

(2x+3x+4x)^(1/2) = 5x
(9x)^0,5 = 5x
4,5 = 5x
x = 5/4,5
x = 1,111...

JKL;!!!!! · Post by **JKL;!!!!!** » Tue Mar 25, 2008 11:16 pm

i don't get this...
i'm onlyy grade 5 =(

Yuryeong · Post by **Yuryeong** » Tue Mar 25, 2008 11:24 pm

Really?

Well is not too hard...

Let's explain with the basic...

"+" Is diferent of "-"
"."(Multiply) Is diferent of "/"
= Equal(Doh)

1 + x = 2
If I pass 1 to the other side of the "=" I turn this 1 to the diferent simbol(Or better, +1, when pass to the other side will be -1)

x = -1 + 2
or
x = 2 - 1
x = 1

2x, 3x(Is always 2.x or 3.x, you always multipy the X)
If it is:
1x(1x is the same as only x) + 1 + x = 2

2x + 1 = 2

2x = 2 - 1
2x = 1
(Pass the 2 of the X, 'cause X is ".", you pass in "/")
x = 1/2
x = 0,5

0,5 + 1 + 0,5 = 2

I SUCK AS A TEACHER!

JKL;!!!!! · Post by **JKL;!!!!!** » Tue Mar 25, 2008 11:38 pm

i see...
isn't that pre-algebra?

Yuryeong · Post by **Yuryeong** » Tue Mar 25, 2008 11:41 pm

I think... Dunno... XD
I know how to do but i don't know the name of the things ;p

JKL;!!!!! · Post by **JKL;!!!!!** » Tue Mar 25, 2008 11:44 pm

---------------------------_
did you know that 0.99 = 1?
because 0.33 = 1/3, so, 0.99 = 1!

Yuryeong · Post by **Yuryeong** » Tue Mar 25, 2008 11:45 pm

Cool... You smart

Do you know that in binary:
1+=10
10+1 = 11
11 + 1 = 100

Tom · Post by **Tom** » Wed Mar 26, 2008 12:37 am

correct answer: .36 or 9/25

proof:

Code: Select all

(2x + 3x + 4x)^(1/2) = 5x
√(9x) = 5x
9x = 25x^2
9 = 25x
x = .36 or 9/25

new problem:

Doctor What · Post by **Doctor What** » Wed Mar 26, 2008 1:01 am

I'm gonna give this a shot.

7sin(40) = 5sin(X)

awww crap, I can't find my ti-84...

hobobuster · Post by **hobobuster** » Wed Mar 26, 2008 1:04 pm

hahah mine is at home too

Post by **CX gamer** » Wed Mar 26, 2008 2:57 pm

7sin(40) = 5sin(X)
<=> sin(X) = 0.8999026535611550585170077387017
<=> X = asin(0.8999026535611550585170077387017)
<=> X = 64.14527° + k*360 (k ∈Z)
or X = 115.85473° + k*360 (k ∈Z)

Peemore · Post by **Peemore** » Wed Mar 26, 2008 3:27 pm

JKL;!!!!! wrote:i don't get this...
i'm onlyy grade 5 =(

no way!

Post by **atomtengeralattjaro** » Wed Mar 26, 2008 3:47 pm

hey dont believe a word/number he says

Tom · Post by **Tom** » Wed Mar 26, 2008 4:27 pm

If 7x = 4y, and (y/z) = (7/5), then (x/z) = ?

Peemore · Post by **Peemore** » Wed Mar 26, 2008 4:29 pm

(4/5)

Post by **atomtengeralattjaro** » Wed Mar 26, 2008 4:34 pm

yea..

7x=4y
y=(7/4)x

y/z=7/5
(7/4)x/z=7/5
35/20 x/z = 28/20
35x/z = 28
x/z=28/35=4/5

Tom · Post by **Tom** » Wed Mar 26, 2008 4:41 pm

excellent job.

okay, one more easy one before a harder one.

If the line containing the points (a,3) and (b,2) has a slope of 1/7, then a-b=?