direct variation

posted by .

could someone please help me with these problems i am having trouble.

If y=36 when x =6 find x when y = 42
If y=-18 when x=6 find x when y=6
If y =12 when x= 15 find x when y =21
If y=-6.6 when x=9.9 find y when x =6.6
If y=6 when x=(2/3)find x when y=12

those are the problems you don't have to do all just at least show me step by step how you arrived at the answer thank you so much for helping

take the first one:

y1/y2 = x1/x2

y1=36 x1 is 6
y2=42 x2 is ?
36/42=6/x solve for x
x=42*6/36 =7

check my thinking.

hyng bbncnnh gbgbn

These are proportion problems
(1) 6:36=x:42 Which is the same as (6*42)/36=x
(2)6:18=x:6 Which is the same as (6*6)/18=x
(3) 15:12=x:21 I think you can do them now
(4)9.9:-6.6=6.6:y Watch where the y is located here.
(5)(2/3):6=x:12 Be sure to handle the fraction correctly.

In general, a proportion is two ratios a:b=c:d
a and d are called the extremes and b and c the means.
The fundamental relation is a*d=b*c The product of the extremes = the product of the means.
You can also think of it in terms of fractions a/b = c/d. in terms of fractions both ratios are different names for the same fraction. One is a multiple of the other. In the first one we have
6:36 or 6/36=1/6
We want to find x such that x/42 = 1/6 so x=42*(1/6)
You can verify that 1/6 = 6/36 = 7/42.
The fraction 1/6 would be the fraction in lowest terms in integers. In some places finding that lowest reducible integer fraction is very important. Other times we can't find such an integer ratio, e.g. if the numbers are irrational.

If y =12 when x= 15 find x when y =21

y=kx 21

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Stuck on Algebra 1

    This is kind of like the first question I asked, and I'm still having a little trouble on it. The Ordered pairs in each exercise are for the same direct variation. Find the missing value. (-2,8) and (x,12) I'm not sure how to work …
  2. Math

    I am doing Direct Variation in math. I don't understand how to do it. It would be very helpful if you helped me with these problems: Is each equation a direct Variation?
  3. Math: Direct Variation

    what are the formulas that illustrates direct blinear variation ?
  4. PreCalculus

    I'm having trouble with these problems.. Could someone please explain how to find the domain of either of these functions?
  5. Algebra 2

    I am trying to figure out if these problems are Direct Variation, Inverse Variation, or Neither. Could someone please check my answers?
  6. Algebra 2

    Is the relationship between the variables in the table a direct variation, an inverse variation, both, or neither?
  7. Algebra 2 Honors

    Hey, we recently started a topic in class that I don't understand well, I just want to post 6 of the problems and ask if they're right or not (some of them I have no idea how to do). 1. If a varies directly as b and b = 18 when a = …
  8. Algebra worksheet

    Hello. My algebra teacher gave me this worksheet last week and everyone had to bring it yesterday and I haven't done it yet. Can someone please help me. He said Friday is the last day or he's going to take away some points. I've been …
  9. math

    Is the relationship between the variables in the table direct variation, inverse variation, both, or neither?
  10. algebra

    Hi I'm having trouble with this question I don't understand it at all. This is the question: Suppose y varies directly with x, and y = 15 and x = 5. Write a direct variation equation that relates x and y. What is the value of y when …

More Similar Questions