What is the proper way to present mathematical problems on online forums?

In summary, the conversation was about solving a problem involving the equation |a| = |h| |b| and finding the value of h. The solution involved using the equation h = -|a|/|b| to get a negative value of h, as required by the problem statement. The conversation also discussed the importance of adhering to the PF standard and presenting a readable problem.
  • #1
Member warned to take more care when posting images

Homework Statement


upload_2018-6-27_23-29-31.png


Homework Equations


Is my solution correct? If not then please point out the mistakes and help me solve this question in the right way. Thanks in advance.

The Attempt at a Solution


upload_2018-6-27_23-31-3.png
 

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  • #2
|a| = |b| |h|
so
|h| = |a| / |b|
and h<0
 
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  • #3
.Scott said:
|a| = |b| |h|
so
|h| = |a| / |b|
and h<0
After finding h, can we solve this question by matrix method? (The way I did)
 
  • #4
You have h = -|b|/|a|.
It should be h = -|a|/|b|.

Then solve with b = a/h
 
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  • #5
.Scott said:
You have h = -|b|/|a|.
It should be h = -|a|/|b|.

Then solve with b = a/h
If we make |h| the subject, it will be |h|= |a| / |b|. The answer will be positive. So | | signs will reverse the signs and give a negative value of h?
 
  • #6
Right. We need to make h negative.
|a|/|b| is positive over positive, which is positive.

Per the problem, we need h to be negative...
So, h = -|a|/|b|
 
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  • #7
.Scott said:
Right. We need to make h negative.
|a|/|b| is positive over positive, which is positive.

Per the problem, we need h to be negative...
So, h = -|a|/|b|
How will it become negative?

If I use the equation |a| = |h| |b| then how can I get a negative value of h?
 
  • #8
Muhammad Danish said:
How will it become negative?

If I use the equation |a| = |h| |b| then how can I get a negative value of h?

By using the equation: h = -|a|/|b|

Here's the sequence:
|a| = |h| |b|
|a|/|b| = |h|
so either h = |a|/|b|
or h = -|a|/|b|

But we know from the problem statement that it must be negative.
 
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  • #9
.Scott said:
By using the equation: h = -|a|/|b|
By removing ''| |'' from h, the other side will become negative?
 
  • #10
Muhammad Danish said:
By removing ''| |'' from h, the other side will become negative?
I added some text to my last post.
Here it is again:

Here's the whole sequence:
|a| = |h| |b|
|a|/|b| = |h|
so either h = |a|/|b|
or h = -|a|/|b|

But we know from the problem statement that it must be negative.
 
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  • #11
.Scott said:
I added some text to my last post.
Here it is again:

Here's the whole sequence:
|a| = |h| |b|
|a|/|b| = |h|
so either h = |a|/|b|
or h = -|a|/|b|

But we know from the problem statement that it must be negative.
Like this?
upload_2018-6-28_0-27-19.png
 

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  • #12
Yes!
 
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  • #14
Muhammad Danish said:

Homework Statement


View attachment 227388

Homework Equations


Is my solution correct? If not then please point out the mistakes and help me solve this question in the right way. Thanks in advance.

The Attempt at a Solution


View attachment 227389

Your problem is totally unreadable. Please take the trouble to adhere to the PF standard, by typing out the statement of the problem. If you cannot do that, you should at least make sure you take a proper photo that will come out readable by the rest of the world.
 

1. What is vector multiplication?

Vector multiplication is a mathematical operation that combines two vectors to produce a new vector. There are two main types of vector multiplication: dot product and cross product. The dot product results in a scalar value, while the cross product results in a vector value.

2. How do you calculate the dot product of two vectors?

The dot product of two vectors can be calculated by multiplying the corresponding components of the two vectors and then adding the products together. For example, if vector A = [a1, a2, a3] and vector B = [b1, b2, b3], the dot product (A · B) would be equal to (a1 * b1) + (a2 * b2) + (a3 * b3).

3. What is the purpose of vector multiplication?

Vector multiplication is used in many fields of science and engineering, including physics, engineering, and computer graphics. It allows us to model and solve complex physical and mathematical problems by representing quantities such as force, velocity, and acceleration as vectors.

4. Can you multiply a vector by a scalar?

Yes, it is possible to multiply a vector by a scalar (a single value). This results in the vector being scaled or stretched in the same direction without changing its direction. For example, if vector A = [a1, a2, a3] and the scalar value is k, then the result would be kA = [ka1, ka2, ka3].

5. How is the cross product of two vectors different from the dot product?

The cross product of two vectors is a vector value, while the dot product is a scalar value. Additionally, the cross product yields a vector that is perpendicular to both of the original vectors, while the dot product yields a scalar value that represents the projection of one vector onto the other.

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