SOLUTION: if y varies inversely as x and y =25 when x =4, find x when y is 10

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Question 204298: if y varies inversely as x and y =25 when x =4, find x when y is 10
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Since "y varies inversely as x" it means that y=k%2Fx where "k" is some fixed number.



y=k%2Fx Start with the given equation


25=k%2F4 Plug in x=4 and y=25


25%2A4=k Multiply both sides by 4


k=100 Multiply


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y=k%2Fx Go back to the given equation


y=100%2Fx Plug in k=100


10=100%2Fx Now plug in y=10. The goal now is to solve for x


10x=100 Multiply both sides by 'x'


x=100%2F10 Divide both sides by 10


x=10 Reduce


So x=10 when y=10 (note: this is just a coincidence).