SOLUTION: For the following problem, y varies inversely with x. If y = 14 when x = 12, find x when y is 21.

Algebra ->  Equations -> SOLUTION: For the following problem, y varies inversely with x. If y = 14 when x = 12, find x when y is 21.      Log On


   

Question 1056248: For the following problem, y varies inversely with x.
If y = 14 when x = 12, find x when y is 21.
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
y varies inversely with x.
y%22%22=%22%22k%2Fx

If y = 14 when x = 12, 
Substitute that in

14%22%22=%22%22k%2F12

Solve for k

Multiply both sides by 12

168%22%22=%22%22k

Substitute that in 

y%22%22=%22%22k%2Fx

y%22%22=%22%22168%2Fx  <-- that's the formula

find x when y is 21.
Substitute 21 for y

y%22%22=%22%22168%2Fx

21%22%22=%22%22168%2Fx

Multiply both sides by x

21x%22%22=%22%22168

Divide both sides by 21

x%22%22=%22%228

Edwin