Why don't you divide 30 divided by 6, so do 45 divided by 9? It is much easier.

Yup. That's correct but when the questions get harder the other method makes it both clearer and easier to understand

help me understand what varation mean

*variation* |ˌve(ə)rēˈāSHən| _noun_ *1* a change or difference in condition, amount, or level, typically with certain limits: _regional variations in house prices_ | _the figures showed marked variation from year to year._ • *Astronomy*: a deviation of a celestial body from its mean orbit or motion. • *MATHEMATICS*: a change in the value of a function due to small changes in the values of its argument or arguments. • (also magnetic variation) the angular difference between true north and magnetic north at a particular place. • *Biology*: the occurrence of an organism in more than one distinct color or form. *2* a different or distinct form or version of something: _hurling is an Irish variation of field hockey._ • *Music*: a version of a theme, modified in melody, rhythm, harmony, or ornamentation, so as to present it in a new but still recognizable form: _there is an eleven-bar theme followed by seven variations and a coda_ | figurative : _variations on the perennial theme of marital discord._ • *Ballet*: a solo dance as part of a performance. *DERIVATIVES* variational |-SHənl|adjective *ORIGIN* late Middle English (denoting variance or conflict): from Old French, or from Latin _variatio(n-)_, from the verb _variare_ (see vary) .

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Algebra (all content)

Course: Algebra (all content) > Unit 13

Lesson 7: Direct and inverse variation

Proportionality constant for direct variation

Name: Proportionality constant for direct variation
Uploaded: 2011-06-21T23:30:09Z
Description: Worked example: y is directly proportional to x, and y=30 when x=6. Find the value of x when y=45.

Google Classroom

Worked example: y is directly proportional to x, and y=30 when x=6. Find the value of x when y=45. Created by Sal Khan and Monterey Institute for Technology and Education.

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ryan
Posted 11 years ago. Direct link to ryan's post “help me understand what v...”
help me understand what varation mean
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(1 vote)
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- DY (darryl-yeo.com)
  Posted 10 years ago. Direct link to DY (darryl-yeo.com)'s post “*variation* |ˌve(ə)rēˈāSH...”
  variation |ˌve(ə)rēˈāSHən|
  noun
  1 a change or difference in condition, amount, or level, typically with certain limits: regional variations in house prices | the figures showed marked variation from year to year.
  • Astronomy: a deviation of a celestial body from its mean orbit or motion.
  
  • MATHEMATICS: a change in the value of a function due to small changes in the values of its argument or arguments.
  • (also magnetic variation) the angular difference between true north and magnetic north at a particular place.
  
  • Biology: the occurrence of an organism in more than one distinct color or form.
  2 a different or distinct form or version of something: hurling is an Irish variation of field hockey.
  • Music: a version of a theme, modified in melody, rhythm, harmony, or ornamentation, so as to present it in a new but still recognizable form: there is an eleven-bar theme followed by seven variations and a coda | figurative : variations on the perennial theme of marital discord.
  • Ballet: a solo dance as part of a performance.
  DERIVATIVES
  variational |-SHənl|adjective
  ORIGIN late Middle English (denoting variance or conflict): from Old French, or from Latin variatio(n-), from the verb variare (see vary) .
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The Beast
Posted 11 years ago. Direct link to The Beast's post “Why don't you divide 30 d...”
Why don't you divide 30 divided by 6, so do 45 divided by 9? It is much easier.
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(8 votes)
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- Aditi
  Posted 10 years ago. Direct link to Aditi's post “Yup. That's correct but w...”
  Yup. That's correct but when the questions get harder the other method makes it both clearer and easier to understand
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  (10 votes)
Wadhia Sultana
Posted 5 years ago. Direct link to Wadhia Sultana's post “can we do this math diffe...”
can we do this math differant way.i think this way is little travel for me.
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(3 votes)
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Robert
Posted 3 years ago. Direct link to Robert's post “how would I do it if it w...”
how would I do it if it was NOT an example of direct variation?
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Lyla
Posted 3 years ago. Direct link to Lyla's post “Sorry, I would like to kn...”
Sorry, I would like to know if there are ways to solve this type of variation questions:

If x+y ∝z , when y is constant and z+x ∝y , when x is constant, then prove that, x+y+z ∝yz , where x, y, z are variables

I feel like I'm guessing randomly every time :/

Thanks a lot :D
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(1 vote)
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Jonah
Posted 3 years ago. Direct link to Jonah's post “What if we are only given...”
What if we are only given the y/x value?
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madalena seltsam
Posted 10 years ago. Direct link to madalena seltsam's post “how do find y in direct v...”
how do find y in direct variation? could you please show me an example.
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(1 vote)
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dumb boii
Posted 9 years ago. Direct link to dumb boii's post “The example that its giv...”
The example that its giving in the video it kind of help me but in one part I don't really understand it like I'm kind of confused.
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(1 vote)
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SongBird
Posted 9 years ago. Direct link to SongBird's post “what do you do when the y...”
what do you do when the y isnt divisible by the x
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- Andrius
  Posted 9 years ago. Direct link to Andrius's post “this is a second (the sam...”
  this is a second (the same) question from you. There is never a case when y isnt divisable by the x. If you have such case please share it with us.
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Logan McElwee
Posted 5 years ago. Direct link to Logan McElwee's post “im lost how do you find ...”
im lost how do you find the constant variation of {(-5,3),(-5,1)(0,0)(10,-2)
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(1 vote)
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Video transcript

y is directly proportional to x. If y equals 30 when x is equal to 6, find the value of x when y is 45. So let's just take this each statement at a time. y is directly proportional to x. That's literally just saying that y is equal to some constant times x. This statement can literally be translated to y is equal to some constant times x. y is directly proportional to x. Now, they tell us, if y is 30 when x is 6-- and we have this constant of proportionality-- this second statement right over here allows us to solve for this constant. When x is 6, they tell us y is 30 so we can figure out what this constant is. We can divide both sides by 6 and we get this left-hand side is 5-- 30 divided by 6 is 5. 5 is equal to k or k is equal to 5. So the second sentence tells us, this gives us the information that y is not just k times x, it tells us that y is equal to 5 times x. y is 30 when x is 6. And then finally, they say, find the value of x when y is 45. So when y is 45 is equal to-- so we're just putting in 45 for y-- 45 is equal to 5x. Divide both sides by 5 to solve for x. We get 45 over 5 is 9, and 5x divided by 5 is just x. So x is equal to 9 when y is 45.