SOLUTION: Please help me determine whether the equation defines y as a function of x: 3x+7y=21

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Question 987834: Please help me determine whether the equation defines y as a function of x: 3x+7y=21
Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

A function is a relation (so, it is the set of ordered pairs) that does not contain two pairs with the same first component.
3x%2B7y=21+
7y=-3x%2B21+
y+=+%28-3%2F7%29x+%2B3+ defines a function since we can easily find the output y when the input, x, is given.
If x=1, then y+=+%28-3%2F7%29%2A1+%2B3+=>y+=+-3%2F7+%2B21%2F7=18%2F7+ for example.
Or, if x=7, then y+=+%28-3%2F7%29%2A7+%2B3+=>y+=+-3+%2B3=0+.
So every x has a corresponding y value.

+graph%28+600%2C600%2C+-10%2C10%2C+-10%2C+10%2C+%28-3%2F7%29x+%2B3%29+