Question 312483: if y varies directly as x and y = 4 when x= -2, find y when x = 30.
A) -4/15
B) 60
C) -60
D) 4/15
Answer by rapaljer(4671)   (Show Source):
You can put this solution on YOUR website! If y varies directly as x, then y=kx.
Since y=4, when x=-2, plug it into the formula above, and you have
y=kx
4=k(-2)
Solve for k, k=-2
Now, y = -2x, so if x=30
y=-2*30=-60.
The correct answer is C.
If you or anyone needs extra help with the Proportions and Variation, please see my own website. Click on my tutor name "Rapalje" anywhere in algebra.com. On my information page, click on the link to my Homepage. Once you find my Homepage, look for the link "Basic, Intermediate, and College Algebra: One Step at a Time." Then choose "Intermediate Algebra", and look in Chapter 2. Sections 2.09 contains a detailed explanation of VARIATION, complete with examples, exercises, and most importantly, ALL of the answers. Many of the exercises in these sections are explained IN COLOR in the corresponding "Math in Living Color" pages. My own students used to think my explanations were a LOT easier to understand than the traditional textbooks. You might like my website for an alternative explanation, or for extra problems for practice! It's all FREE. If you get tired of math, then see the Joke Page!! If you like it please recommend it to friends.
Dr. Robert J. Rapalje, Retired
Seminole State College of Florida
Altamonte Springs Campus
|
|
|
