Show that the solution is not suitable....

  • MHB
  • Thread starter mathlearn
  • Start date
In summary: Therefore, the length of PB is a negative number, making it unsuitable for representing a physical measure.
  • #1
mathlearn
331
0
Data

The solution of the quadratic equation $5x^2-5x-11=0$ is $x=\frac{5-7\sqrt{5}}{10}$

PB=$2x-1$ cm

Where do I need help

By substituting the solution $x=\frac{5-7\sqrt{5}}{10}$ in the expression above for the length of $PB$ , show that this solution is not suitable.

Many Thanks :)
 
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  • #2
What kind of number cannot represent a physical measure?
 
  • #3
MarkFL said:
What kind of number cannot represent a physical measure?

A fraction or a decimal :)
 
  • #4
mathlearn said:
A fraction or a decimal :)

No...what's the formula for the distance between two numbers on a number line?
 
  • #5
MarkFL said:
No...what's the formula for the distance between two numbers on a number line?

(Thinking) I'm sorry i don't know
 
  • #6
Suppose that $p$ and $q$ are two real numbers. Then the distance $d$ between these numbers, given in units, on a real number line is:

\(\displaystyle d=\sqrt{(p-q)^2}=|p-q|\)

So, what is the range of values we can get for $d$?
 
  • #7
MarkFL said:
Suppose that $p$ and $q$ are two real numbers. Then the distance $d$ between these numbers, given in units, on a real number line is:

\(\displaystyle d=\sqrt{(p-q)^2}=|p-q|\)

So, what is the range of values we can get for $d$?

My Apologies MarkFL , I don't know that either (Doh)
 
  • #8
mathlearn said:
MarkFL said:
What kind of number cannot represent a physical measure?
A fraction or a decimal :)

I think we can measure 1/6 of an inch, or 0.12 cm, can't we?
But a length cannot be negative... (Thinking)
 
  • #9
I like Serena said:
I think we can measure 1/6 of an inch, or 0.12 cm, can't we?
But a length cannot be negative... (Thinking)

Agreed (Nod) Now what is meant above is that as $x$ obtained by simplifying the quadratic equation is negative It is not suitable?...(Thinking)
 
  • #10
mathlearn said:
PB=$2x-1$ cm

By substituting the solution $x=\frac{5-7\sqrt{5}}{10}$ in the expression above for the length of $PB$ ...

After doing that, what do you find?
 
  • #11
greg1313 said:
After doing that, what do you find?

Yeah why not simplify it (Sun)

With PB=$2x-1$ given,

$2*\frac{5-7\sqrt{5}}{10}-1$

$\frac{5-7\sqrt{5}}{5}-1$

$\frac{5-7\sqrt{5}}{5}-\frac{5}{5}$

$\frac{-7\sqrt{5}}{5}$
 

Related to Show that the solution is not suitable....

1. What does it mean to show that a solution is not suitable?

Showing that a solution is not suitable means providing evidence or demonstrating that the solution is not appropriate or effective for a given problem or situation.

2. Why is it important to show that a solution is not suitable?

It is important to show that a solution is not suitable because it helps to prevent wasting time, resources, and efforts on implementing a solution that will not effectively address the problem at hand.

3. How can you determine if a solution is not suitable?

Determining if a solution is not suitable involves carefully evaluating the characteristics and requirements of the problem and comparing them to the proposed solution. This can include conducting experiments, gathering data, and consulting with other experts in the field.

4. What are some common reasons for a solution to be deemed not suitable?

Some common reasons for a solution to be deemed not suitable include not addressing all aspects of the problem, not being feasible or practical to implement, not being cost-effective, and not being supported by evidence or research.

5. What should be done if a solution is determined to be not suitable?

If a solution is determined to be not suitable, it is important to go back to the drawing board and reassess the problem, the available resources, and potential solutions. It may be necessary to modify the current solution or explore alternative options to find a more suitable solution.

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