In example c the function is already solved for y and y is defined to be the positive square root of (x+9). Note: the square root symbol means take ONLY the principal (or non-negative) square root of the quantity. That is why this example is a function. However, if the problem had been given as y^2=x+9, then you would have to solve it for y by taking square roots of both sides. This would then give y = plus or minus the square root of (x+9) and it would not be function. Hope this helps.
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Great video!!! Showed numerous amounts of examples, kudos!!!
Thank you. Glad you liked it. Please let me know if you have any questions.
for c, why would the answer not be plus or minus 4, making it not a function?
In example c the function is already solved for y and y is defined to be the positive square root of (x+9). Note: the square root symbol means take ONLY the principal (or non-negative) square root of the quantity. That is why this example is a function. However, if the problem had been given as y^2=x+9, then you would have to solve it for y by taking square roots of both sides. This would then give y = plus or minus the square root of (x+9) and it would not be function. Hope this helps.