Find and approximate value square root of 3 using the roots of the graph.

In summary, using a graph of function $y=3-(x-1)^2$ with negative and positive roots of -0.8 and 2.7 respectively, the approximate value for $\sqrt{3}$ can be found by solving for $x$ in the equations $x-1=\pm\sqrt{3}$, which results in $x=1+\sqrt{3}$ and $x=1-\sqrt{3}$, giving approximate values of 2.7 and -0.7, respectively. Other methods of finding the square root using the roots of a graph, such as using the quadratic formula, may also be possible but are not applicable in this particular problem.
  • #1
mathlearn
331
0
Using a graph of function $y=3-(x-1)^2$ which has got its negative & positive root s-0.8 and 2.7 respectively, Find an approximate value for $\sqrt{3}$.

Any suggestions on how to begin? Should I be using the quadratic formula here?

Many Thanks :)
 
Last edited:
Mathematics news on Phys.org
  • #2
mathlearn said:
Using a graph of function $y=3-(x-1)^2$ which has got its negative & positive roots -0.8 and 2.7 respectively, Find an approximate value for $\sqrt{3}$.

Any suggestions on how to begin? Should I be using the quadratic formula here?

Many Thanks :)
This problem is much easier than you are making it.

If $y= 3- (x- 1)^2= 0$ then $(x- 1)^2= 3$ so $x- 1=\pm\sqrt{3}$. If x= -0.8, what is $\sqrt{3}$? If x= 2.7, what is $\sqrt{3}$?
 
  • #3
HallsofIvy said:
This problem is much easier than you are making it.

If $y= 3- (x- 1)^2= 0$ then $(x- 1)^2= 3$ so $x- 1=\pm\sqrt{3}$. If x= -0.8, what is $\sqrt{3}$? If x= 2.7, what is $\sqrt{3}$?

If x=-0.8, I guess It should be -0.7

$x- 1=+2.7$
$x- 1+1=2.7+1$

$x- 1=+2.7$
$x=3.7$(Oops! Looks like something is wrong)(Doh) $x- 1=-0.7$
$x- 1+1=-0.7+1$

$x=0.3$(Oops! Looks like something is wrong Again !)(Doh)

I would like to know the different way's of approximating a square root using the roots of a graph. Like one I already know is using the quadratic formula
 
  • #4
mathlearn said:
$x- 1=+2.7$
Where are you getting this from? You were told told that $x-1=\pm\sqrt{3}$ and not $x-1=2.7$. More precisely, $x-1=\sqrt{3}$ when $x\approx2.7$ and $x-1=-\sqrt{3}$ when $x\approx-0.8$.
 
  • #5
Evgeny.Makarov said:
Where are you getting this from? You were told told that $x-1=\pm\sqrt{3}$ and not $x-1=2.7$. More precisely, $x-1=\sqrt{3}$ when $x\approx2.7$ and $x-1=-\sqrt{3}$ when $x\approx-0.8$.

Oh! my apologies (Smile).

Then,

$x-1=\pm\sqrt{3}$
$2.7-1=\pm\sqrt{3}$
$1.7=\pm\sqrt{3}$

$0.7-1=\pm\sqrt{3}$
$-1.7=\pm\sqrt{3}$

Thanks (Smile), I would like to know the different ways of doing this kind of a problem 'to find the square root using the roots of a graph'. Like one way would be to use the quadratic formula.
 
  • #6
mathlearn said:
$2.7-1=\pm\sqrt{3}$
This is incorrect because the left-hand side is positive.

mathlearn said:
I would like to know the different ways of doing this kind of a problem 'to find the square root using the roots of a graph'. Like one way would be to use the quadratic formula.
I don't know of another way to solve this particular problem.
 
  • #7
Evgeny.Makarov said:
This is incorrect because the left-hand side is positive.

(Smile) Why is that ?, +1.7 is an approximate value for the square root of 3. (Smile) Please comment.
 
  • #8
mathlearn said:
Why is that ?
Evgeny.Makarov said:
because the left-hand side is positive.
which cannot be said about $\pm\sqrt{3}$.
 
  • #9
Evgeny.Makarov said:
which cannot be said about $\pm\sqrt{3}$.

Hopefully, I guess this is correct now (Happy)

$x-1=\pm\sqrt{3}$ , \(\displaystyle \therefore\) $2.7-1=+\sqrt{3}$
$1.7=+\sqrt{3}$

$0.7-1=- \sqrt{3}$
$-1.7=- \sqrt{3}$
 
  • #10
Evgeny.Makarov said:
$0.7-1=- \sqrt{3}$
$-1.7=- \sqrt{3}$
Where did you get $0.7$ from? And $0.7-1\ne-1.7$.

Evgeny.Makarov said:
More precisely, $x-1=\sqrt{3}$ when $x\approx2.7$ and $x-1=-\sqrt{3}$ when $x\approx-0.8$.
 
  • #11
mathlearn said:
Hopefully, I guess this is correct now (Happy)

$x-1=\pm\sqrt{3}$ , \(\displaystyle \therefore\) $2.7-1=+\sqrt{3}$
$1.7=+\sqrt{3}$
Better:- $x- 1= \sqrt{3}$ so $x= 1+ \sqrt{3}$ which is approximately 2.7

$0.7-1=- \sqrt{3}$
$-1.7=- \sqrt{3}$
Better: $x- 1= -\sqrt{3}$ so $x= 1- \sqrt{3}$ which is approximately -0.7.
 
  • #12
No, in the original problem $x$ is known and one is asked to estimate $\sqrt{3}$.
 
  • #13
Evgeny.Makarov said:
Where did you get $0.7$ from? And $0.7-1\ne-1.7$.

(Doh) Sorry , I have mistyped -0.7 as +0.7

HallsofIvy said:
Better:- $x- 1= \sqrt{3}$ so $x= 1+ \sqrt{3}$ which is approximately 2.7Better: $x- 1= -\sqrt{3}$ so $x= 1- \sqrt{3}$ which is approximately -0.7.

(Nod) Yes Isolating 'X' on the RHS would look neater and tidier.

Evgeny.Makarov said:
No, in the original problem $x$ is known and one is asked to estimate $\sqrt{3}$.

Yes (Nod)
Many Thanks (Happy)
 

1. What is the square root of 3?

The square root of 3 is an irrational number, meaning it cannot be expressed as a simple fraction. It is approximately 1.7320508075688772.

2. How can I find the square root of 3?

The square root of 3 can be found by using the roots of the graph. This involves finding the point on the graph where the line crosses the x-axis at the value of 3, and then finding the corresponding y-value. This y-value will be the square root of 3.

3. Can I approximate the value of the square root of 3?

Yes, the square root of 3 can be approximated by using the roots of the graph method described above. This will give you a close approximation of the actual value.

4. Is the square root of 3 a rational or irrational number?

The square root of 3 is an irrational number, meaning it cannot be expressed as a simple fraction. It is a non-repeating, non-terminating decimal.

5. Why is it important to be able to find and approximate the square root of 3?

The square root of 3 is a fundamental mathematical concept that is used in many calculations and formulas in various fields, such as physics, engineering, and finance. Being able to find and approximate it accurately is essential for solving complex problems and making accurate calculations.

Similar threads

Replies
1
Views
1K
Replies
2
Views
749
  • General Math
Replies
3
Views
1K
  • General Math
Replies
16
Views
2K
  • Precalculus Mathematics Homework Help
Replies
11
Views
516
Replies
3
Views
1K
Replies
7
Views
3K
Replies
18
Views
3K
  • General Math
Replies
1
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
2K
Back
Top