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Wednesday, October 12, 2005

Yesterday's Scribe

First of all, I'd like to say sorry guys for not putting up a post yesterday. I know I was the scribe, but my internet wasn't working all that well. But, my post, for yesterday isn't going to be much, and I seriously apologize for it.

Okay so here we go:

Yesterday's class, Mr. K put up questions on the board to solve with our calculator to find the roots.

1. x² + 6x - 11 = 0

2. 7x² - 5x + 1 = 0

3. x² - √x-1 = 0

4. x³ + x = 30

5. Where does the line y = 2x + 3 cut the curve y = x² + 2x

(The thing is guys, I sort of got confused on which buttons to press on the calculator to find the roots. I'll try my best, but please, feel free to corect me).

So for the first question, x² + 6x - 11 = 0,
On your graphing calculators, you press the Y = button on the the above blue keys
And type in the the equation x² + 6x - 11, and hit the GRAPH button
Hit the TRACE button, and then 2nd CALC and choose 2: zero
It will say Left Bound? on the screen, move the cursor by hitting the left arrow key to bring you below the x-axis
And hit enter
It will then say Right Bound? on the screen, move the cursor by hitting the right arrow key to bring you above the x-axis.
Hit enter again.
It will then say Guess?, but Mr. K said don't guess, so at this point, hit enter.
And on the screen it will say
x = 1.472136

For the second question 7x² - 5x + 1 = 0, you practically do the same thing.
But the thing is, this equation, doesn't have roots.
You can type it in, and once you press GRAPH, you can hit the ZOOM key and choose 1: ZBox.
This will allow you to draw a box where the parabola curves, to see if it actually touches the x-axis.
And in this case, it doesn't. So we label this problem as no solution.

For the third question x² - √x-1 = 0, is like the second question. It has no roots, it's above the x-axis. So this problem is also marked as no solution.

Question four, x³ + x = 30, would have to be changed to: x³ + x - 30 = 0. And this is where Mr. K mentions that because it has a degree of 3, the most roots it would have is three.

And the last question, five. "Where does the line y = 2x + 3 cut the curve y = x² + 2x". Type both equations when you press the Y = button. And hit GRAPH, then you press the TRACE button. You then press 2nd CALC, and choose 5: intersect, and move the cursor the an intersection by moving the right arrow key. Press ENTER, it will then say First Curve? and press enter again, then it will say Second Curve? and press enter again, and it will ask you to Guess? but, you don't guess of course, and just hit enter. And it will give you the intersection.

Afterwards, Mr. K put us into groups of three, and we did a problem solver. Ones that we've done before. We struggled, and then he put the answers on the board. And that was about it for the class. Sorry if I missed anything, I really tried to re-cap from yesterday.

And Richard sorry I picked you, but hey, look at it this way, now Aichelle can win the race. And everyone else can comment on a wonderful post. ;)


At 10/12/2005 6:19 PM, Blogger Richy said...

Haha... I still won this race. Hahahahaha. Oh shoot I still have to scribe... Dang

At 10/12/2005 6:25 PM, Blogger AichelleS. said...

awesome post! lol hopefully I'll be first on Richard's scribe


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