सदस्य: Melody

Guest:
The end of an exit ramp from a highway is 17.5 feet above the highway. The angle of inclination of the ramp is 3 degrees. How long is the base of the ramp?

Draw the right angled triangle.
The ramp is the hypotenuse.
the height is opposite the angle.
So you have 3 degrees, the hypotenuse and the opposite side.
What trig ratio are you going to use?

Melody27 Feb 2014

+118692

john:
how to solve equation using the quadratic formula

take a look at this video and see if it helps
http://www.youtube.com/watch?v=H5AM1bzqCQw

Here is a work page if you want
http://www.mathsisfun.com/algebra/quadratic-equation.html

also, if you have problems remembering it this might help. (unfortunately the visuals don't seem to be working any more but the sound is still worth while.)
http://www.youtube.com/watch?v=O8ezDEk3qCg

Melody27 Feb 2014

+118692

Zezimama:
(csc^2 x - cot^2 x)/(1 + tan^2 x ) = cos^2 x

Hi Zezimama,
Here you go
140227 Prove Trig Identity.JPG

Melody27 Feb 2014

#94

+118692

thanks Reinout

HARD ONE
3,4,4,5,8,10 and the magic number is 147

147
= 150 - 3
= 10*5*3 - 3*1
= 10*5*3 - 3* 4/4
= 3 (10*5 - 4/4)

Melody26 Feb 2014

+118692

No I don't get it !

Melody26 Feb 2014

+118692

+11

Thanks reinout-g,

I am bound to be wrong but I think that it is irrelevant.
Whether you picked the right one or the wrong one to start with there is still a box with nothing in it that can be opened so what difference does it make.
I am obviously wrong since Reinout Says that this is a hard problem.
Anyone got any other (better) ideas

Melody26 Feb 2014

#92

+118692

reinout-g:
The answer is (8*2+25)*7+100

I used the same method as always trying to divide the magic number and if it gave no workable solutions then add and substract a little from the number.

This didn't give me much so I then tried working the other way around multiplying 3 and 100 to try and get to 387.
Since it was obvious that the 100 was of no use in multiplications I figured it might be used in a addition or substraction computation.

This gave me the hint towards 287 which brought me back to my original method.
This gave me the division by 7 and finally I tried working my way to the 41 that was left by dividing after some additions and substractions again.

HARD ONE
2,3,8,7,25,100 And the magic number is 387

I had a different method. This is how i did it.
387
=300 + 75 + 12
=3*100+3*25+3*8/2
factor out the 3 and you get
3(100+25+8/2)
Would you like to post the next one reinout? If you would then just copy the question post down and change the numbers for the hard one. Just make sure that it works first. If you don't do it i will do it later. Thanks so much.
Melody.

Melody26 Feb 2014

+118692

I did not fully understand Bob's answer so i asked for some clarification. Here is his answer.

The method I used is known as a 'trial solution method', and it is just that. You try something, if it works fine, if not try something else. With practice it's usually possible to guess what the solution looks like.
Have you done any work on second order ODE's with constant coefficients ? That's where your most likely to come across it. It's a commonly taught method for finding the Particular Integral. The general solution of such an equation will consist of the Particular Integral plus a Complementary Function (which is the solution of the corresponding homogeneous equation and which will contain two arbitrary constants). It's pretty much the same for the difference equation we are discussing, its general solution consists of two parts, a Particular Solution (which is what I've found), plus the solution of the corresponding homogeneous equation, (which I haven't).
140226 Bob's answer to 'answer'.JPG

I had to really think about the last step but this is what Bob did
-6An + 28A - 6B = n
therefore
-6A = 1 and 28A-6B = 0
A = -1/6
and with substitution
28*(-1/6) = 6B
B = -28/36 = -7/9

therefore
T _n = (-1/6)n - 7/9

I have not looked at the 2nd equation yet. If you are still around you can try it by yourself and see how you go.

Melody26 Feb 2014

यूजर का नाम	Melody
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