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  Discussion about math, puzzles, games and fun.   Useful symbols: √ ∞ ≠ ≤ ≥ ≈ ⇒ ∈ Δ θ ∴ ∑ ∫ π -

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Topic review (newest first)

bobbym
2012-05-01 19:49:17

Take what amberzak is doing in the other threads. Geogebra does those in under a minute!

anonimnystefy
2012-05-01 19:44:58

I agree. Geogebra has many cool and useful functions for something that is generally thought of as a graphing software.

bobbym
2012-05-01 19:40:47

I did not say you can not get it, but the thinking has already been done for us
in Geogebra.

anonimnystefy
2012-05-01 19:38:07

Why not just enter the difference of the two functions?

bobbym
2012-05-01 19:37:20

That does not get the integral between two curves. Geogebra does that for us, M does not.

anonimnystefy
2012-05-01 19:36:14

Integrate[f(x),{x,a,b}] ?

bobbym
2012-05-01 19:31:28

Yep, M has nothing like it.

anonimnystefy
2012-05-01 19:29:43

Do you mean the integral function?

bobbym
2012-05-01 08:58:18

Did you read post #2?

anonimnystefy
2012-05-01 08:34:32

How so?

bobbym
2012-05-01 08:33:08

For this type of problem, Geogebra is more powerful than M.

anonimnystefy
2012-05-01 08:30:06

Ok then.

I am thinking about making another one of these.

bobbym
2012-05-01 08:26:47

Yes, I left that for the readers to get.

anonimnystefy
2012-05-01 08:07:07

Hi bobbym

Why don't you zoom in? That way you have "more" space to put more points. I think you can get a 100 even.

bobbym
2012-05-01 07:30:00

Hi;

Another one came up. We need the area of the red shape in the first picture.

1) Input f(x) = x+1. A straight line will be drawn.

2) Input g(x)=6x-x^2-3. A parabola will be drawn.

3) Get the points of intersection of the two equations using the intersection tool. The points will be labelled A,B.

4) Go into options, labelling and check no new objects. Also hide the labels of A and B.

5) Use the polygon tool and carefully click on A and then place as many points as you on that curve until you finish at B and then click A to complete the polygon. I managed 19 points on the curve. See the second picture.

6) Read off the value of poly1, I got 4.48347. That is a good estimate of the area of the red area.

Now geogebra has an incredible command that does this for us.

7) Input integral[f,g,x(A),x(B)] and immediately our area is hsaded darker and in the algebra pane you will see a new value of 4.5. That is the exact answer. I am quite close. How did you do?

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