direct variation

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 ?
then
36/42=6/x solve for x
and
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

  1. 👍 0
  2. 👎 0
  3. 👁 327

Respond to this Question

First Name

Your Response

Similar Questions

  1. Math

    The coordinates of the end-points of a line segment PQ are P(3,7) and Q(11,-6). Find the coordinates of the point R on the y-axis such that PR = QR. Please include the workings, as I would like to be able to perform these problems

  2. Math 8R - help!!!!!!!!!!!!!

    Multi-Step Equations Solving Equations with Variables on Both Sides 1) 5y + 4 = 4y + 5 11a + 9 = 4a + 30 2w + 3 = 4w - 5 2) 3a - 10 = 4 + a 2x - 1 = x - 3 6n + 4 = n - 11 3) 29r + 4 = 28 + 13r 7x - 11 = -19 + 3x 4) b + 3 = 2b - 7

  3. math

    5) A student answered 86 problems on a test correctly and received a grade of 98%. How many problems were on the test, if all the problems were worth the same number of points?

  4. Physics 1 College Level

    A planet/moon has a mass of 77.89 × 1023 kg and a radius of 7.9 × 106 meters. What is g on the surface to the nearest hundredth of a m/s2? Once again, not really sure where to go with this. Out of the 10 problems I've only had

  1. Statistics-Probability

    An instructor will choose 3 problems from a set of 7 containing 3 hard and 4 easy problems. If the selection is made at random, what is the probability that only the hard problems are chosen?

  2. algebra

    A student missed 11 problems on a Chemistry test and received a grade of 65%. If all the problems were of equal value, how many problems were on the test? Round off your answer to the nearest integer. X= # of problems 11= 3 of

  3. mathematics

    Hey guys, I am just starting this new topic, and I have been finding it really confusing. I have an assignment due and I was wondering if someone could help me solve these problems? Thanks! List all the subsets of each set. -I

  4. Algebra II

    Solve x^4 - 12x - 5 = 0 given that -1 + 2i is a root. I’ve used synthetic division to get the answers x = 1 +/- 2i , 1 +/- sqrt 2 I’ve having trouble checking the answers though because of that imaginary number. How can I

  1. psychology

    Gavin, a seventh grader, has more trouble in school than many of his peers, particularly with word problems in math and other areas that aren't concrete and tangible. In spite of high motivation, he still struggles, and new

  2. Math

    Here's a couple examples from my homework. If someone could help me solve this by showing me step by step what to do, it would be so great. Also, any websites that would show me the steps too. Thanks so much. I have to get all my

  3. English

    Can someone please proofread my essay on snitching and help fix any grammar error to make it flow better. Did I correctly use the word liabilities? Snitching is the cause of a lot of problems that go on in the work environment

  4. Math

    I am having problems understanding how to solve problems like the following: a2 + b2 = c2 Please help me where I can understand solving problems such as the one above.

You can view more similar questions or ask a new question.