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Rosa 13
Postad: 4 maj 2020 17:35

How to solve 0=x²+3x−3 ?

Hej! I need help!
"Använd grafritande räknare.
Rita grafen till y=x²+3x−3.
Avläs funktionens nollställen med två värdesiffror.
Börja med det minsta talet."
What does it mean?
How to solve this?

Qetsiyah 6503 – Livehjälpare
Postad: 4 maj 2020 18:11

Do you not understand swedish?

I says you should do it with a calculator, find the zeros and write them down with two significant figures. What calculator do you have?

Smaragdalena 78453 – Lärare
Postad: 4 maj 2020 18:16

Har du en grafritande räknare? Vilken modell är det? Man matar in på lite olika sätt på olika fabrikat.

Rosa 13
Postad: 4 maj 2020 19:31 Redigerad: 4 maj 2020 19:37
Qetsiyah skrev:

Do you not understand swedish?

I says you should do it with a calculator, find the zeros and write them down with two significant figures. What calculator do you have?

I calculate result as x= 3(1-x) ,

then, how to solve  X continually?

Skaft 2373 – F.d. Moderator
Postad: 4 maj 2020 19:37 Redigerad: 4 maj 2020 19:38

You're meant to plot the function and use that to see which values of x make the function zero.

Rosa 13
Postad: 4 maj 2020 19:37 Redigerad: 4 maj 2020 19:38
Smaragdalena skrev:

Har du en grafritande räknare? Vilken modell är det? Man matar in på lite olika sätt på olika fabrikat.

I calculate result as x= 3(1-x),

then, how to solve  X continually?

AlvinB 4014
Postad: 4 maj 2020 19:38
Rosa skrev:
Qetsiyah skrev:

Do you not understand swedish?

I says you should do it with a calculator, find the zeros and write them down with two significant figures. What calculator do you have?

I calculate result as x= 3(1-x) ,

then, how to know what  X should be.

When solving for xx, we want to isolate xx on one side of the equals sign. You have xx's on both sides, which is not what we want.

Do you understand what the exercise is saying? Do you have a graphing  calculator?

(Do you speak Swedish?)

Rosa 13
Postad: 4 maj 2020 19:42
AlvinB skrev:
Rosa skrev:
Qetsiyah skrev:

Do you not understand swedish?

I says you should do it with a calculator, find the zeros and write them down with two significant figures. What calculator do you have?

I calculate result as x= 3(1-x) ,

then, how to know what  X should be.

When solving for xx, we want to isolate xx on one side of the equals sign. You have xx's on both sides, which is not what we want.

Do you understand what the exercise is saying? Do you have a graphing  calculator?

(Do you speak Swedish?)

True. That's why I could not solved it. I found the two points on demos.com. 

But I am thinking whether can solve it without the graphing. 

AlvinB 4014
Postad: 4 maj 2020 20:36

Well, the exercise wants you to use a graphing calculator, but it is possible to solve without a calculator.

Are you familiar with the quadratic formula? (pq-formeln in Swedish)

It can be used to solve quadratic equations (andragradsekvationer) like this one.

Rosa 13
Postad: 4 maj 2020 20:49
AlvinB skrev:

Well, the exercise wants you to use a graphing calculator, but it is possible to solve without a calculator.

Are you familiar with the quadratic formula? (pq-formeln in Swedish)

It can be used to solve quadratic equations (andragradsekvationer) like this one.

No, I don't how how to solve quadratic formula. That's reason I posted the question on here. 

Do you know where I can learn about how to solve quadratic formula? Video would be great for me. Thanks!

AlvinB 4014
Postad: 4 maj 2020 20:54

Here are two video lectures on the quadratic formula. One in English:

https://www.khanacademy.org/math/algebra/x2f8bb11595b61c86:quadratic-functions-equations/x2f8bb11595b61c86:quadratic-formula-a1/v/using-the-quadratic-formula

and one in Swedish:

https://www.youtube.com/watch?v=UgfgUCPwOZA

(You haven't yet told us whether or not you speak Swedish, so I gave you videos in both languages)

Rosa 13
Postad: 4 maj 2020 21:34 Redigerad: 4 maj 2020 21:35
AlvinB skrev:

Here are two video lectures on the quadratic formula. One in English:

https://www.khanacademy.org/math/algebra/x2f8bb11595b61c86:quadratic-functions-equations/x2f8bb11595b61c86:quadratic-formula-a1/v/using-the-quadratic-formula

and one in Swedish:

https://www.youtube.com/watch?v=UgfgUCPwOZA

(You haven't yet told us whether or not you speak Swedish, so I gave you videos in both languages)

Thank you very much, AlvinB! 

I can speak Swedish in simply way :-)

Rosa 13
Postad: 5 maj 2020 10:05
Skaft skrev:

You're meant to plot the function and use that to see which values of x make the function zero.

Thank you very much!

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