All Answers

+130561

Have you tried the calculator on this site??

It will compute that for you.

CPhillMar 30, 2014

Mar 29, 2014

+130561

A trapezium ABCD, AB parallel to DC, BC is perpendicular to both AB and DC. A (4, 2), B (16, 8), C (13,14), D(5, 10). Lines AD and BC produced to meet at P. Find the coordinates of P.

OK, let's find an equation for both lines AD and BC.....then, we can find their intersection.

Equation of line AB
Slope = (10-2) /(5-4) = 8
So, writing in point/-slope form, we have
y - 2 = 8(x -4)
y - 2 = 8x - 32
y = 8x - 30

Equation of line BC
Slope = (14-8)/(13-16) = 6 / -3 = -2
So, writing in point-slope form, we have
y - 8 = -2(x - 16)
y - 8 - -2x + 32
y = -2x + 40

Setting these equal and solving for x, we have
8x - 30 = -2x + 40
10x = 70
x = 7
To find the y coordinate of the intersection point, "plug" the x value into one of the two equations. Using the first equation, we have
y = 8(7) -30
y = 56 -30
y = 26

Then point "P" = (7, 26)

CPhillMar 29, 2014

There are two ways to do this. This example is nice to just add the two equations (you could also subtract for similar problems)

-4x+y=6
+
-5x-y=21
-----------
-9x+0=27

---> x=-3

Then plug into one of the equations and solve for y

-4*(-3)+y=6

= 12+y=6

--> y=(-6)

You should then check the other equation is true

--> -5*(-3)-(-6)=21

= 15+6=21 which is true.

Alternatively you can simply solve for y in terms of x in the first equation ---> y=6+4x
then substitute this equation for y into the second equation where ever you see y (be careful with the negative signs), solve for x, and use that result to find y. I recommend doing it both ways to make sure you don't make any mistakes.

Hope this helps!

GuestMar 29, 2014

+130561

First, let's total what she spent at the mall.

7.24 + 13.78 + 24.71

Let's call the amount of money she took to the mall "x"

Then, the amount of money that she had after her friend paid her back was just

x + 20

So the total amount of money she had (x + 20) - (amount she spent) = 49.27

Setting this up as an equation , simplifying, and solving for x,, we have

x + 20 - 45.73 = 49.27

x - 25.73 = 49.27

x =

49.27 + 25.73

Therefore, she brought $75 to the mall.

CPhillMar 29, 2014

+135

kateeelllyyynn:
99% CI for the population proportion of voters opposing a new tax was calculated to be (.68,.76). What was the sample proportion of voters who oppose the new tax

The CI of a population proportion is

(p - z SE, p + z SE)

where p is the mean sample proportion, SE is its standard error, and z is the critical z-value of the confidence interval.

In other words, the requested sample proportion is the mean of the CI, which is:

p = (.68 +.76) / 2

Additionally, we can estimate the number of voters n.

From the CI we know that z SE = (.76 - .68) / 2 = 0.04.
The critical z-value of a 99% CI is z = 2.575.
So SE = 0.04 / 2.575 = 0.015534.

The SE of a proportion is:

SE = √ (p (1 - p) / n)

Therefore:

n = p (1 - p) / SE ² = .72 (1 - .72) / .015534 ² = 835

I like SerenaMar 29, 2014

#11

+130561

Thanks, Stu. I discovered this site some years ago. It's quite excellent. He used to have a more thorough section on Trig as well as a whole section devoted to Linear Algebra, too.
The one on Linear Algebra was FIFTY times better than the class I took in college!! I suppose that the powers-that-be at Lamar University forced him to take these down, but I'm only guessing. Still, it's a good resource.......thanks for posting it to the forum.

CPhillMar 29, 2014

#10

+1313

[size=150]Pauls online notes[/size]

Great site for revision and learning, with easy navigation. Examples you can understand, solutions, rules, pdf downloadable etc.
A really great site.

http://tutorial.math.lamar.edu/Extras/AlgebraTrigReview/SimpRatExp.aspx <--- highlight right click and goto.

Includes, all calc, 1, 2, 3, trig etc all of what you will need- cheat sheets, common math errors made and more.

StuMar 29, 2014

+893

RUM Troll:
Rom:
xy = -49
(x-3)2 - 9 = 49
(x-3)2 = 58
x-3 = +/- sqrt(58)
x = 3-sqrt(58) OR x = 3+sqrt(58) and the corresponding y's are y=3+sqrt(58) OR y=3-sqrt(58)
clearly x+y=6
xy = 9 - 58 = -49

-------------------
Clearly x+y=6. Clearly, this is a "Lovely math question." Clearly, the answer isn't.
You probably meant this:
y=(49/(sqrt(2)*sqrt(29)-3)) y=(-49/(sqrt(2)*sqrt(29)+3))

Recommendation to Rom: Go a little lighter on the late-afternoon martinis and you won't fuckup as much.

by RUM Troll
Professional Troll Association post ID DD0A4439FEAB242A903A13B5E0937A43

xy = 9 - 58 = -49

BertieMar 29, 2014

#86

+118725

Hi all,
Today was very quiet which is normal for a Friday/Saturday. Thank you Chris for answering the couple of questions.
Enjoy your weekend.
Melody.

MelodyMar 29, 2014

+118725

3l3v3n11:
simplify (2u^-5v^-1)^-3

It will be mucheasier to see what you are doing if your fractions are upright.

Have a look at this post on how to deal with negative indices.

If you have any questions, please ask.

http://web2.0calc.com/questions/negative-exponents-negative-indices

Just highlight the address -> left click -> choose "goto"

MelodyMar 29, 2014

+1313

Professional Troll:
by Professional Troll.

yah drongo!
No need for swearing in a forum that is used by all ages.

And since you-like to-correct so manny of the freee help-asssistance reppplies that are given to posts by those using thisss site with a common purpose let me clarify your mistakes.
Mistake one is assuming what you have to say is of any consequence to the running of the site. That is, thisss site at its heart is to assist people and a forum at that by definition gives room to have feed back and multiple opinions, ideally on the post in question, to best assist the original poster in the question raised. That was also your second mistake, to assume that this site gives some kind of guaranteeee of the information being correct although it is presumed that each reply does try to be,... or that those replying know as much knowledge as your pertain to owning in your post (generally nothing related to maths). Your third mistake was using inappropriate language, and your last mistake was your attempt to have an IQ. Good bye sir,

LOLALOTATDRONGOS

Don't get your panties in a knot over human nature and put your creativity into the arts, that way you can de-construct abstracts to your hearts content, plausibly argue why a proccess is wrong and not look foolish, or have to justify your self countless timesss. BAHAHAHA you making me weep from fits of laughter.

StuMar 29, 2014

+1313

So sad are you. Good luck with your life sir.

StuMar 29, 2014

Mar 28, 2014

+130561

Each gets 3/5 of a carrot.

Proof.......5 * (3/5) = 3

CPhillMar 28, 2014

+130561

simplify (2u^-5v^-1)^-3

So we have

(2^(-3)) * (u^15) * (v^3) =

1/(2^3) * (u^15) * (v^3) =

1/8 * (u^15) * (v^3) =

(u^15) * (v^3) / 8

And there you go......

CPhillMar 28, 2014

Melody:
pancakes:
What the XXXX?

Hello Pancakes,
I don't mind you bopping along around in here. I want this to be a site that is both friendly and helpful for children, BUT the language you have used here is not acceptable.
Find yourself some cleaner words with which to express you amazement. There are plenty of them. Use your imagination.
Melody.

----
By Pottymouth Troll
Yes, I have to agree, the language you have used here is not acceptable!

You could stick to vulgar fractions or Farey sequences, or you could say, “What the b****y h**l is this fucking s**t?”
You should appreciate this anyway. The above equation is how someone might flip pancakes. That is different than the equation for flipping someone off.

BTW There is someone at another site by the name Flapjack. You two should get together and make a few waffles.

From watch your fucking Pottymouth Troll.
Professional Troll Association post ID E2DC28AEB5BA2BD3D963F15F5DB5198A

GuestMar 28, 2014

Rom:
Quote:
Light of wavelength 630 nm travels through a diffraction grating. A third-order bright fringe is observed at 42.0°. How many lines per cm does the diffraction grating have? Answer with four significant digits.

-----------------------
Re: Is it Physic or physics
By Rum Troll
Postby Rom » Wed Mar 19, 2014 4:27 pm
Light of wavelength 630 nm travels through a diffraction grating. A third-order bright fringe is observed at 42.0°. How many lines per cm does the diffraction grating have? Answer with four significant digits.
---
A slightly convoluted solution going from nanometers to micrometers, but if you are doing physics it should be transparent. What should not be transparent is using 680 nm when 630 nm is the required value. So 3450 lines per cm is correct.

In Rom’s defense it was straight away after his martinis lunch, so he was a little off center. How much off center? about -2.82 degrees. If the angle of incidence to the diffraction grating is -2.82 degrees then 3280 lines per cm for 630 nm lambda is correct.

Another point about this post is Rom’s use of inline images. It’s impressive. It is proof that he has graduated beyond a slide rule.
Suggestion to Rom: try 42 proof instead of 42% martinis.

Is it physic or physics?
By Physic Troll
Professional Troll Association post ID EAC4676AB83890D4E9673A87624574C0

GuestMar 28, 2014

Pale Blue Moon
By Biteme Troll
-----
This is one reason I became a Professional Troll.

You correct a mistake and make a funny joke on the funny users name, the moderator jumps your a*s as if you lobed a grenade in the room. Kamikaze Rom the error master shoves a grenade up your “behind” to finish you off.

You then apologize. I know your apology is an extreme form of sarcasm because finding an apologetic Russian, who isn’t standing before a firing squad, is less likely than finding a polite “East” German. It was brilliant, but it seemed too real. No one got it.

You should have said “Now it will be for me to fly to the Blue Moon, after you BITE ME!”
This keeps the apologetic tone then conveys the sarcasm as a surprise. It is like tweaking your girlfriends nose after kissing her. In that instance you will get slapped. Here, you will get virtual a*s jumps and grenades shoved up your “behind.” But it is great!

“Bite me” in English is funny. Americans and some Australians will get it. It is close to and just as funny as your “укусить меня” but the translation is lost. Literally, it is closer to “Чью по этому.” But you have to use the English.

You should join the Professional Troll Association. There are strict rules you have to follow, but it will help with your English. Melody and Rom are the largest posters here. Until today, I didn’t target them because… Well because I did not know what post to pick. Think of a lion in the vast hunting ground of zebras. Which one do you pick? The white zebra with the black stripes or the Black zebra with the white stripes? Too much choice. Eventually, the lion makes a decision. The lion has lunch, but the zebra does not like it much.

Professional Troll Association post ID 17F8B7C9A5CD1BEE97CD83DDE2C877D0

GuestMar 28, 2014

Rom:
xy = -49
(x-3)2 - 9 = 49
(x-3)2 = 58
x-3 = +/- sqrt(58)
x = 3-sqrt(58) OR x = 3+sqrt(58) and the corresponding y's are y=3+sqrt(58) OR y=3-sqrt(58)
clearly x+y=6
xy = 9 - 58 = -49

-------------------
Clearly x+y=6. Clearly, this is a "Lovely math question." Clearly, the answer isn't.
You probably meant this:
y=(49/(sqrt(2)*sqrt(29)-3)) y=(-49/(sqrt(2)*sqrt(29)+3))

Recommendation to Rom: Go a little lighter on the late-afternoon martinis and you won't fuckup as much.

by RUM Troll
Professional Troll Association post ID DD0A4439FEAB242A903A13B5E0937A43

xy = 9 - 58 = -49

GuestMar 28, 2014

I like Serena:
Irreverent Statistic:
What is the probability that "I like Serena" will make a comment on a question that either states the obvious or is trivial and useless.

My preferred mode of operation is to state the obvious, which then leads to ooh and aah - now I understand!
This is usually how mathematics works: once you see it, it is obvious and in retrospect you can't understand why you didn't see it before.
Ah well, often it helps if someone points out the obvious.

Re: statistics Obvious
by Obvious Troll
**
Postby I like Serena " Tue Mar 11, 2014 4:32 pm
My preferred mode of operation is to state the obvious, which then leads to ooh and aah - now I understand!
This is usually how mathematics works: once you see it, it is obvious and in retrospect you can't understand why you didn't see it before.
Ah well, often it helps if someone points out the obvious.
--------
Are you sure they are not saying "I understand" just to shut you up? That is "Shut your Pi hole" in math speak.

Your "preferred mode of operation is to state the obvious?" Statistically, your preferred mode of operation is to post "stamps of approval" like a tomcat spraying his territory. This is now obvious and in retrospect you can't understand why you didn't see it before.

Your tomcat behavior indicates, obviously, you are a late teenage to early 20s male.
But on this post http://web2.0calc.com/questions/ap-stat-please-help
you say, "If you register with this link, you'll give me a brownie point."

A brownie is a member of an organization for preteen girls. This is very confusing (not obvious). So maybe you are a preteen girl. The Professional Troll Association rules forbid trolling young children. If it is just your wish then the rules are not applicable.

Statistically Obvious by Obvious Troll
Professional Troll Association post ID 029B5F6DC44C14389F41BFE01F8C56CE

GuestMar 28, 2014

натали:
С одного поля собрали по 45 ц пшеницы с гектара, а с другого - по 35 ц с гектара. Всего было собрано 1900ц. На следующий год урожайность первого поля уменьшилась на 20%, второго на 15%, а весь урожай уменьшился на 330 ц. Найдите площадь каждого поля.