SOLUTION: How do I determine whether an equation defines y as a function of x? For example 5x+7y=10

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Question 921900: How do I determine whether an equation defines y as a function of x?
For example 5x+7y=10
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
IF for each x there is at most one y, that defines y as a function of x.
5x%2B7y=10<--->7y=10-5x<--->y=%2810-5x%29%2F7<--->y=%28-5%2F7%29x%2B10%2F7
defines y as a function of x because for each value of x you can calculate one unique value of y.
x%5E2%2By%5E2=25<--->y%5E2=25-x%5E2<--->system%28y=sqrt%2825-x%5E2%29%2C%22or%22%2Cy=-sqrt%2825-x%5E2%29%29 does not define y as a function of x, because for some values of x there are 2 possible values for y.