Untitled Document
   

Dr Kang's Statement
 
Write Date : 15-02-14 08:55
Varies directly means...
 Writer : 관리자
View : 777  
   https://answers.yahoo.com/question/index?qid=20090709002608AAO4TOP [431]

What does "varies directly" mean?

Could someone please expalin to me what it means when two variables "vary directly", and help me solve the following problem?

If "a" varies directly with "b" squared, and if b=4 and a=3, what is the value of "a" when b=8?
2 answers

Answers

Best Answer:  it means x=ky. or in this case a=kb. k being the constant of variation. so 3=k4. a=3 when b=4. so divide both sides to find the constant of variation, k. you get k=3/4. so a=3/4b. if b=8, a=3/4(8).
a=6, when b=8

pikajew64 · 6 years ago
0
1
Comment

Equations can vary either directly or inversely.

If y varies directly with x, for example, a typical equation would look like this: y = 5x (with "5" being a placeholder for your constant). As x increases, y increases, hence they vary DIRECTLY.

If y varies inversely with x, you may see something like: y = 5/x. In this equation, as x increases, y DECREASES (which is considered an inverse relationship).

So, in your problem, the basic equation is: a = k(b^2) ***The k here just represents the unknown constant***

a = k(b^2)

Plug in 4 for b and 3 for a, as per the first part of the problem.

3 = k(16)
3 = 16k
k = 3/16

So, now we take the value that we found for k and use it to solve the second part of the problem.

a = 3/16 (b^2)

plug in 8 for b

a = 3/16 (64)
a = 12

Ta-da! If you have any more questions, feel free to ask.

EDIT: Pikajew6, I think you may have glossed over the beginning of the problem where the poster said, " "a" varies directly with "b" squared...".


 
 

No Title Writer Date View
공지 Try the following question 관리자  08-27 83
공지 Naver 전문정보 강박사님 논문 소개 "영어교육계 명불허전" 제… 관리자  01-28 2325
공지 Glen Learning Center, English Verbs 관리자  04-15 1034
공지 Glen Learning Center, Bio-Chemistry Lab 관리자  12-07 320
공지 강박사님, 조선일보, 동아일보 발언대 효과적인 영어교육 (2) Dr Kang  11-19 2485
24 Try the following question 관리자  08-27 83
23 Dornsife 60-second seminar: Oil and the Middle East 관리자  12-14 169
22 Glen Learning Center, Bio-Chemistry Lab 관리자  12-07 320
21 Michael Jackson- 강박사님은 마이클잭슨 고등학교 모교에서 15… 관리자  12-03 209
20 동문여러분 USC 한국 동문회 회장 박인구입니다. (동원, 부회장… 관리자  10-25 232
19 Really Learn English 관리자  06-01 262
18 Steve 관리자  04-13 594
17 test 관리자  06-01 718
16 USC Alumni 관리자  05-23 671
15 Today's Assignment 관리자  04-22 740
14 Draw Three-Dimensional Figures, Textbook 관리자  04-21 661
13 Word Problems into Equations 관리자  04-15 699
12 Varies directly means... 관리자  02-14 778
11 Glen Learning Center, English Verbs 관리자  04-15 1034
10 English Study easily 관리자  05-30 1117
 1  2