 # Komentarze Non-figure related, Pre-Calculus Help!

• Ill just wanted to thank all who helped me. You're all the bestttt.
3 l. temu Gotcha but creamsoda below was stating the outside but i read you mention the inside too in your comment?

Only the boundary and outside the boundary.

Hint: Use a test point in the provided inequality that lies inside the circle and you will get a false statement. I.e., test the center point of the circle, (3,-2).
3 l. temu Oh! Are you a physics major? I ask because you mentioned ray transfer matrix analysis D:

yup.
3 l. temu First problem is a simple of equations:
``` Perimeter of a rectangle: P= 2l + 2w (I) The additional condition is: l = 4w (II) ```
(if l is the length an w the width)
Now you put (II) in (I) and get:
`P = 2*(4w) + 2w = 10w`
... which is easy to solve, with P = 200 ft :)
I don't see, where you'd need matrices for this, as you can solve this problem without them ... (or did I misinterpret the question?)
I'll try to plot the other two with gnuplot ...
Edit:
So the third one:
Pokaż zawartość spoileraUkryj zawartość spoilera Zoomed in: To plot the second function and solve this system of equations, you just need to solve the second for y:
``` x-y+1 = 0 |+y y = x+1 ```
As you can see in the pictures above, the curves meet at point (0,1).
Edit2:
Second problem:
Pokaż zawartość spoileraUkryj zawartość spoilera So this is obviously a circle.
The simplest equation for a circle in cartesic coordinates is:
`x² + y² = r²`
Which would result in a circle around the point (0,0) with the radius of r. Hopefully you remember pythagoras here. ^^ In this problem r² = 16, so you get a circle with radius of 4.
But why is it displaced:
When you see ...
`(x-a)² + (y-b)² = r²`
This means, the center of your circle is displaced by a on the x-axis, and by b on de y-axis. In this problem a = 3 and b = -2.
So your circle has the center in (3,-2) and a radius of 4.
This kind of a basic pattern, one should remember ... if you see something similar, you should remember instantly "oh, that's a circle!". :)
Next thing is the inequality ...
As the problem wants all x's and y's for which the term ((x-3)²+(y+2)²) is greater than or equal 16, this means all x's ansd y's on the outside and the border of the circle solve this inequality.
I hope you can follow me ... english is not my first language, so it's a little hard to explain everything in detail. >_< Well, it's a good practice, as I'll have to use english soon in my studies too ... ._.
And, although I could need some \$\$, you don't need to send me moneys for this. xD It was nice to cool down a little from ray transfer matrix analysis ...

Oh! Are you a physics major? I ask because you mentioned ray transfer matrix analysis D:
3 l. temu I am glad that people posted the answers. I got a refresher on certain topics. Lol.
3 l. temu Oh my this is killing me.
Can you please verify if this is correct
s29.postimg.org...

The 2nd line, 2nd multiplication is incorrect, it should be 4*4.
3 l. temu Just FYI, none of these are matrices. Only one of them comes somewhat close as a system of nonlinear equations.

Oh well...
3 l. temu Oh my this is killing me.
Can you please verify if this is correct

s29.postimg.org...

First problem is a simple of equations:
``` Perimeter of a rectangle: P= 2l + 2w (I) The additional condition is: l = 4w (II) ```
(if l is the length an w the width)
Now you put (II) in (I) and get:
`P = 2*(4w) + 2w = 10w`
... which is easy to solve, with P = 200 ft :)
I don't see, where you'd need matrices for this, as you can solve this problem without them ... (or did I misinterpret the question?)
I'll try to plot the other two with gnuplot ...
Edit:
So the third one:
Pokaż zawartość spoileraUkryj zawartość spoilera Zoomed in: To plot the second function and solve this system of equations, you just need to solve the second for y:
``` x-y+1 = 0 |+y y = x+1 ```
As you can see in the pictures above, the curves meet at point (0,1).
Edit2:
Second problem:
Pokaż zawartość spoileraUkryj zawartość spoilera So this is obviously a circle.
The simplest equation for a circle in cartesic coordinates is:
`x² + y² = r²`
Which would result in a circle around the point (0,0) with the radius of r. Hopefully you remember pythagoras here. ^^ In this problem r² = 16, so you get a circle with radius of 4.
But why is it displaced:
When you see ...
`(x-a)² + (y-b)² = r²`
This means, the center of your circle is displaced by a on the x-axis, and by b on de y-axis. In this problem a = 3 and b = -2.
So your circle has the center in (3,-2) and a radius of 4.
This kind of a basic pattern, one should remember ... if you see something similar, you should remember instantly "oh, that's a circle!". :)
Next thing is the inequality ...
As the problem wants all x's and y's for which the term ((x-3)²+(y+2)²) is greater than or equal 16, this means all x's ansd y's on the outside and the border of the circle solve this inequality.
I hope you can follow me ... english is not my first language, so it's a little hard to explain everything in detail. >_< Well, it's a good practice, as I'll have to use english soon in my studies too ... ._. 