All Answers

GuestApr 8, 2014

+130561

If 7(s-4)=-3+2s,then s=

Let's simplify this
So we have

7s - 28 = 3 + 2s
Subtract 2s from both sides, giving

5s - 28 = 3
Add 28 to both sides
5s = 31
Dividing by 5 on each side gives us

s = 31 / 5

And that's it.........

CPhillApr 8, 2014

+118725

smitty:
which rule can be used to find the nth term af the following sequence? 1.25,1.5.1.75,2

Well
1.5-1.25=0.25
1.75-1.5=0.25
2-1.75=0.25
So it is an Arithmetic progression.
So you must have to use the nth term of an AP formula.

If you need more help try looking here.
http://www.mathsisfun.com/algebra/sequences-sums-arithmetic.html

MelodyApr 8, 2014

+118725

Zahcary123:
:D Its is 450

Do you want to rethink that Zahcary123?

MelodyApr 8, 2014

Its is 450

GuestApr 8, 2014

#95

+118725

Hi all,
Great answers were provided by reinout-g, CPhill, Alan, guest, A person (really?), -D and Anonymous4338. Thanks guys.
It has been very quiet, Easter is looming so I guess it will get even quieter for a while.
I did learn what the answer to life and all great mysteries is, almost anyway. I guess that is not so bad for one day.
http://web2.0calc.com/questions/math_1702
Night all,
Melody.

MelodyApr 8, 2014

+118725

logan:
if AC=BC=4, what is AB

.

Think of a circle with a radius of 4 units.

Put C at the centre.

Now, A and B can be anywhere at all on the circumference and they will be exactly 4 units from C

they could be the exact same same point and then the distance AB would be 0.
or
they could be on opposite sides of the diameter and then AB would be 8 units
so
0 units <= AB <= 8 units.

MelodyApr 8, 2014

+2354

Melody:
joyopoo:
how do you find the area of a trapezoid

I always think of it as finding the average of the parallel sides, then multiplying by the perpendicular distance between them.

Never thought of it that way

reinout-gApr 8, 2014

#35

+2354

Melody:
Easier one:

Quote:
Ben the hiker wants to spend the night on top of a mountain. He hikes all day long towards the top and camps there overnight. The following day he is taking the same path down towards the bottom when he suddenly looks at his watch en notices that he is at the very same spot at the very same time of the day as the day before on his way up. 'What a coïncidence!' he exclaims!
Give an estimate of the probabilty that a hiker will be at exactly the same spot on the mountain at the same time of the day on his return trip as he was the previous day's hike up the mountain and explain why.

I think that the probability is 1. That means it has to happen.
This is why.
Ben's friend Sven is doing the same hike at exactly the same pace today, from the bottom to the top of the mountain that Ben did yesterday. Ben is on his way down. Somewhere Ben and Sven must pass each other. Obviously it will be the same time for each of them.
Although, Ben might have forgotten to set his watch back to mark the end daylight saving time. (Daylight savings finished on Sunday night in Sydney.) This could cause a problem.
No really, I think that the probablility is one - unless one of them falls and brakes his legs and has to get air lifted out. - then their paths may not cross.

You're right, assuming that all events like a dinosaur eating Ben are very close to 0, the probability of this happening is very close to 1. Did you think about the hard one yet?

reinout-gApr 8, 2014

+118725

joyopoo:
how do you find the area of a trapezoid

I always think of it as finding the average of the parallel sides, then multiplying by the perpendicular distance between them.

MelodyApr 8, 2014

+118725

arcsin is the same a inverse sign. You have to use one of these when you are finding an ANGLE.

asin (7/15) =
or
sin ^-1(7/15) =

If you want the angle in degrees, make sure your calc is set to degrees. If you are using a hand held calc, there will probably be a tiny D at the top of the screen.

MelodyApr 8, 2014

+2354

iam:
Quote:
[size=200][color=#40FF40][center]

Quote:

[/center][/size]what is the hardest math question ever[/color]

Well, naturally, this is a debatable question.

However I think the majority of mathematicians will agree that the 7 millenium prize problems are the most difficult.

Solve any of them (obviously with a solid proof) and you win a $1.000.000 dollars!

Here is the link;http://en.wikipedia.org/wiki/Millennium_Prize_Problems

For the solved math problems,the hardest one I know of would be Fermat's Last Theorem.

The theorem was that the equation a ⁿ + b ⁿ = c ⁿ would not hold for any n>2

The problem turned out to be so complicated that it took 358 years to solve!

http://en.wikipedia.org/wiki/Fermat%27s_Last_Theorem

Reinout

reinout-gApr 8, 2014

#34

+118725

+11

Easier one:

Quote:
Ben the hiker wants to spend the night on top of a mountain. He hikes all day long towards the top and camps there overnight. The following day he is taking the same path down towards the bottom when he suddenly looks at his watch en notices that he is at the very same spot at the very same time of the day as the day before on his way up. 'What a coïncidence!' he exclaims!
Give an estimate of the probabilty that a hiker will be at exactly the same spot on the mountain at the same time of the day on his return trip as he was the previous day's hike up the mountain and explain why.

I think that the probability is 1. That means it has to happen.
This is why.
Ben's friend Sven is doing the same hike at exactly the same pace today, from the bottom to the top of the mountain that Ben did yesterday. Ben is on his way down. Somewhere Ben and Sven must pass each other. Obviously it will be the same time for each of them.
Although, Ben might have forgotten to set his watch back to mark the end daylight saving time. (Daylight savings finished on Sunday night in Sydney.) This could cause a problem.
No really, I think that the probablility is one - unless one of them falls and brakes his legs and has to get air lifted out. - then their paths may not cross.

MelodyApr 8, 2014

+33666

loly:
BEDMAS QUESTION... 52 x 2 / 13 + 5 = ???

There are no Brackets and no Exponents so Division and Multiplication come next (it doesn't matter mathematically in what order multiplication and division are done). Then comes Addition. There is no Subtraction here, but if there were, it wouldn't matter in what order you did the addition and subtraction.

So do 52x2/13 = 8

Then 8+5 = 13

AlanApr 8, 2014

+118725

thanks Stu,

Stu:
1. Differentiate (use appropiate notation)
a) y = x⁹
y'=9x⁸

b) f(x)=5x³ - 3x + 6
f'(x)=15x² -3

c) y = 4x^-5
y'=20x⁴ (You could have used dy/dx= but y' is fine as well - But it should have been y' = -20x^-5-1 = ?) Can you finish this please Stu

2. d/dx (-12x)
f"(x) = -12 Not f"(x) You only use " when you differentiate twice.
The best answer would be d/dx (-12x) = -12

3. differentiate
a) y = (2x+3)⁴
y' = 4*(2x+3)³*2 That is correct but you can simplify this answer.

b) f(x) = x² ( 2x+3)⁴
f'= 2x+4*(2x+3)³*2

b) f(x) = x² ( 2x+3)⁴
For this question you need to use the product rule. If y=uv then y'=uv' + vu'
u=x² so u'=2x
v=(2x+3)⁴ so v'=4(2x+3)³*2 = 8(2x+3)³
Now you have to substitute those values into the formula and simplify the answer.
Could you try doing that please Stu?

Thanks,
Melody.

[/quote]