SOLUTION: Suppose x and y vary inversely, and y = 10 when x = 4. Write a function that models the variation. Then find y when x = 90. I need to show all the steps. Thank you!

Algebra ->  Rational-functions -> SOLUTION: Suppose x and y vary inversely, and y = 10 when x = 4. Write a function that models the variation. Then find y when x = 90. I need to show all the steps. Thank you!       Log On


   

Question 1111385: Suppose x and y vary inversely, and y = 10 when x = 4. Write a function that models the variation. Then find y when x = 90.
I need to show all the steps.
Thank you!
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
I can say:
+y+=+k%2A%281%2Fx%29+
You are given the point ( 4.10 ), so
+10+=+k%2A%28+1%2F4+%29+
+k+=+40+
---------------------
Now I can say:
+y+=+40%2A%28+1%2Fx+%29+
Given +x+=+90+
+y+=+40%2A%28+1%2F90+%29+
+y+=+4%2F9+
----------------------
Check answer:
The new point is ( 90, 4/9 )
+4%2F9+=+k%2A%28+1%2F90+%29+
Multiply both sides by +90+
+40+=+k%2A1+
+k+=+40+
OK