Homework Section

[Custom]

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[Alsatian]

Work out the function that generate the following mixed outputs

a). [3, 0, 4, 1] ---> [9, 1, 13, -3]

b). [4, -2, 5, 0] ---> [13, -2, -8, 10]

c). [3, -1, 3, 0] ---> [-2, 18, 3, 23]

d.) [5, 0 -1, 6] ---> [35, -1, 5, 41]

Hint: Put them in order first!

If its possible, please explain how to work this out, im so stuck, thank you

[Jubin]

Work out the function that generate the following mixed outputs

a). [3, 0, 4, 1] ---> [9, 1, 13, -3]

b). [4, -2, 5, 0] ---> [13, -2, -8, 10]

c). [3, -1, 3, 0] ---> [-2, 18, 3, 23]

d.) [5, 0 -1, 6] ---> [35, -1, 5, 41]

Hint: Put them in order first!

If its possible, please explain how to work this out, im so stuck, thank you

a) First is y=4x-3
b) y= 3x-2
c) is there a typo as you got two times number 3's as x'es. and two different y's for them
d) y= 6x+5



First you got your X's in order [0,1,3,4] and Y's [-3,1,9,13]. And you know that this function is linear [ if you don't know draw this function ]. Now linear function's main equation is y=mx+b. Now replace the matching X and matching Y to that main equation. First I recommend to replace the 0 from x's. so you get the equation -3=m*0+b. Now as any number multiplied by 0 is zero you get -3=b. You got your b value. Now you put b value into the second equation what you get, when you replace the second X's and Y's [ in this case 1 an 1] to the main equation. so you get 1=m*1-3 (-3 is the value of b] so we bring the -3 to the other side and we get 4=m. Now replace m and b to the main equation and there you go y=4x-3.

I'm sure someone else can explain it to you much better and knows an easier way.

 :ps: I got those answers with thx to my program what I have on PC

[Alsatian]

Jubin, Jubin, I cant thank you enough, you have just saved me, thank you sooo much!  :pop:

 :ps: Whats the program you use?

[Jubin]

oh mostly this kind of exercises are being solved with equation systems. Let me demonstrate it on the b) exercise
first still put them in order:
X's [-2,0,4,5] Y's [-8,-2,10,13]. Now take 2 random X's and 2 random Y's [ in this case I take pairs [-2,-8] and [4,10] and put them into the main equation y=mx+b. You'll get the equation system:

-8=m*-2+b => -2m+b=-8
10=m*4+b =>  4m+b=10
now from one of this equation we express either m or b. I take the first equation and b. So it goes like this -2m+b=-8 => b=-8+2m. Now that equation we replace to the second equation.
It goes like this 4m+b=10 => 4m+(-8+2m)=10 => 6m-8=10 => 6m=18 |: 6 => m=3. Now we know what is the value for m also we know that
b= -8+2m therefore b=-8+2*3 => b= -2.
Replace m and b to the main equation and you get y=3x-2.

Edit: Even faster way to solve is this: After you've got your equation system:
-2m+b=-8
 4m+b=10
you subtract them from each other
 -2m+b=-8
-                 it's like    -2m+b-(4m+b)=-8-10
  4m+b=10
=-6m=-18 | : (-6) => m=3. Replace the value of m in any of the equations to get the value of b.

 :ps: The program I use is called Datastudio and it is meant for executing experiments and then analyzing the results.

[Wash]

Please lock this!:P

Why should I talk about homework in my free time?

Don't talk about it then.. it's for people to request help when they are stuck at something with their homework.

[Dmitry]

Oh my god.
I think I need to press X.

How u guys now this ?:P

Some cool place called 'school' xD

I think I might be need some help soon.

Jubin ur damn smart btw.

[Alsatian]

Thanks Jubin

I can help, Im good at maths, sometimes I just need to remember the basics, I complicate it for myself, meh 

[stof]

this topic is gonna come in very usefull cos i suck at school and will be lucky to pass 9th grade

[rJCaiG]

this'll help when i can't be bothered doing some homework this year  good idea

[Clooak]

Decide f´´(x) if f(x) = (5x^3 - 8x^2)/10

Anyone know the answer? :=)

Nevermind I found out the solution.

For those who are woundering Heres how to solve it

f´(x)= (15x^2 - 16x)/10 = f(x)= (30x - 16x)/10
f(2)= (30x - 16x)/10
(30*2- 16*2) /10 = (60-32)/10 = 28/10=2.8

Correct answer would be = 2.8
God I love math

[Chuck_Norris]

We got a assignement to find a song wich could be used for a thriller.
does anyone know what songs could be used for it , and could link me to youtube?
very much appreciated u guys !

[Kitsune]

Decide f´´(x) if f(x) = (5x^3 - 8x^2)/10

Anyone know the answer? :=)

3x-1.6

[Kitsune]

Your solution is wrong because you forgot to change the 16x to 16 when you got the second derivative.

The correct solution:
f(x)=(5x^3-8x^2)/10
f'(x)=(15x^2-16x)/10
f''(x)=(30x-16)/10
      =3x-1.6
f''(2)=3*2-1.6
      =4.4

What you did:
f(x)=(5x^3-8x^2)/10
f'(x)=(15x^2-16x)/10
f''(x)=(30x-16x)/10
      =3x-1.6x
f''(2)=3*2-1.6*2
      =2.8

[Clooak]

My bad, your correct I forgot to derive as u said 16x

Your solution is wrong because you forgot to change the 16x to 16 when you got the second derivative.

The correct solution:
f(x)=(5x^3-8x^2)/10
f'(x)=(15x^2-16x)/10
f''(x)=(30x-16)/10
      =3x-1.6
f''(2)=3*2-1.6
      =4.4

What you did:
f(x)=(5x^3-8x^2)/10
f'(x)=(15x^2-16x)/10
f''(x)=(30x-16x)/10
      =3x-1.6x
f''(2)=3*2-1.6*2
      =2.8