Proportions

[easilyconfuzzeled]

OK here's the deal...I'm taking online classes and I have no teacher support at all. I am taking geometry this year and I'm close to failing. I'm working on proportions and their kicking my butt so i need some help. Here are two questions that are on my assignment;

1) Find x in this proportion.
X=X+2
3 5
X=?

2) Find x in the proportions
5 = 25
2x 4
x=?

All i no is that i need to cross multiply on both of them but from there I am stuck. Can any one help? Please and thank you!

 

[tutor_joel]

Yes, so, cross multiply and see what you get.

#1. 5x = 3(x+2) cross multiplied (assuming I'm reading your notation correctly)

now distribute the 3

5x = 3x + 6 can you take it from here?

 

[easilyconfuzzeled]

5x = 3x + 6 can you take it from here?

no i cant...what do i do after that? :?:

 

[easilyconfuzzeled]

ok wait..i have
5x=3(x+2) then i distribute and get
5x=3x+6..would the next step be to subtract 6 from 5x and its self? or is that wrong and i confused my self even more? lol

 

[tutor_joel]

the next step will be subtract 3x from both sides. You can only add and subtract like terms. That is to say, x terms such as 5x + 3x + 7x, for example, add together to get 15x, likewise, constants add together 5 + 2 = 7, but x terms and constants don't add together. They can multiply and divide together though.

5x - 3x = 3x - 3x + 6
2x = 6

now, divide both sides by 2 in order to isolate the x

\(\displaystyle \frac{2x}{2} = \frac{6}{2}\)

x = 3

so, the second problem is the same approach

 

[tutor_joel]

2.

5(4) = 2x(25) after cross multiplication

20 = 50x

 

[easilyconfuzzeled]

Thank you so much! Hopefully i wont have to ask any more questions on this topic. :lol: