SOLUTION: y varies jointly as a and b, and inversely as the square of c. y=64 when a=14, b=8, and c=4. Find y when a=7, b=4, and c=8. would the answer be: y=(32/2.8)

Algebra ->  Rational-functions -> SOLUTION: y varies jointly as a and b, and inversely as the square of c. y=64 when a=14, b=8, and c=4. Find y when a=7, b=4, and c=8. would the answer be: y=(32/2.8)      Log On


   

Question 885053: y varies jointly as a and b, and inversely as the square of c. y=64 when a=14, b=8, and c=4. Find y when a=7, b=4, and c=8.

would the answer be:
y=(32/2.8)
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39620) About Me  (Show Source):
You can put this solution on YOUR website!
Transcribing to symbols, y=kab%2Fc
y=k%28ab%2Fc%29

Solving for k,
k=yc%2Fab and the given values in the first part mean k=%2864%2A4%29%2F%2814%2A8%29=8%2A4%2F14=16%2F7.

Your equation then is y=%2816%2F7%29%28ab%2Fc%29.
Now use the values given in the second part to find y.

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

y varies jointly as a and b, and inversely as the square of c. y=64 when a=14, b=8, and c=4. Find y when a=7, b=4, and c=8.


y+=+kab%2Fc%5E2



64+=+k%2814%29%288%29%2F4%5E2 ------ Substituting 64 for y, 14 for a, 8 for b, and 4 for c, to determine k 

64+=+112k%2F16 

112k = 64(16) ------ Cross-multiplying

k+=+%2864%2816%29%29%2F112, or k+=+%2864%28cross%2816%29%29%29%2F7cross%28112%29_____64%2F7



y+=+kab%2Fc%5E2

y+=+%28%2864%2F7%29%287%29%284%29%29%2F8%5E2 ------ Substituting 7 for a, 4 for b, and 8 for c

y+=+%28%2864%2F7%29%287%29%284%29%29%2F64_____y+=+%28%28cross%2864%29%2Fcross%287%29%29%28cross%287%29%29%284%29%29%2Fcross%2864%29 

highlight_green%28highlight_green%28y+=+4%29%29

You can do the check!! 



Send comments, “thank-yous,” and inquiries to “D” at MathMadEzy@aol.com.

Further help is available, online or in-person, for a fee, obviously. 



For FREE info and answers to questions about the ASVAB exam, the NYS 3 – 8 city/state wide exams,GENERAL

MATH and HOMEWORK QUESTIONS, or MATH QUESTIONS related to the Regents Integrated Algebra, 

Regents Geometry, Regents Algebra 2/Trigonometry, SHSAT, COOP/HSPT/TACHS, PSAT, SAT, ACT, SSAT/ISEE,

GRE, CLEP, and the TASC/GED, you can visit: http://asvabstudyzone.freeforums.net/.