Constant of Variation

[Iceycold12]

Hello.

Constant of Variation k=y/x

Find the constant of variation for 7y-4x=0.

Re-arrange equation to 7y=4x. (Adding 4x to the other side).
Now use formula.. 7y/4x= 1.75 or 7/4. However, when I use the calculator here: http://mathway.com/problem.aspx?p=algebra it returns 4/7. The same with other questions, it keeps giving me the opposite of my answers. Am I doing something wrong?

 

[Deleted member 4993]

Hello.

Constant of Variation k=y/x

Find the constant of variation for 7y-4x=0.

Re-arrange equation to 7y=4x. (Adding 4x to the other side).
Now use formula.. 7y/4x= 1.75 or 7/4. However, when I use the calculator here: http://mathway.com/problem.aspx?p=algebra it returns 4/7. The same with other questions, it keeps giving me the opposite of my answers. Am I doing something wrong?

7y = 4x

divide both sides by 7

y = (4/7) * x

divide both sides by 'x'

y/x = 4/7 = k

 

[JeffM]

Hello.

Constant of Variation k=y/x

Find the constant of variation for 7y-4x=0.

Re-arrange equation to 7y=4x. (Adding 4x to the other side).
Now use formula.. 7y/4x= 1.75 WRONG

\(\displaystyle 7y = 4x \ implies \dfrac{7y}{4x} = \dfrac{4x}{4x} = 1 \implies \dfrac{4}{7} * \dfrac{7y}{4x} = \dfrac{4}{7} * 1 \implies \dfrac{y}{x} = \dfrac{4}{7}.\)

or 7/4. However, when I use the calculator here: http://mathway.com/problem.aspx?p=algebra it returns 4/7. The same with other questions, it keeps giving me the opposite of my answers. Am I doing something wrong?

I have shown where in YOUR logic you made an error. Moral: don't skip steps, particularly when doing something new.

 

[Lost souls]

Hello.

Constant of Variation k=y/x

Find the constant of variation for 7y-4x=0.

Re-arrange equation to 7y=4x. (Adding 4x to the other side).
Now use formula.. 7y/4x= 1.75 or 7/4.

=> 7y=4x
=>

7y/4x = 1

=> 7y/x=4
=> y/x=4/7