Problem 7.
Answer: This function is not one-to-one.
Why not? Because it is possible to draw a horizontal line through more than one point on the function curve. For example, we can draw a horizontal line through y = 0 on the y axis and it will pass through the two points (-2,0) and (0,0). A one-to-one function will be one where it is impossible to draw any horizontal line through more than one point on the function curve.
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Problem 8.
Answer: -1.
Draw a vertical line through -1 on the x axis. Extend the lin eas much as you can. This vertical line crosses the function curve at (-1,-1) which is the closed endpoint of the first piece. So we see that the input of x = -1 leads to the output y = -1
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Problem 9.
The answer is 4.
To get this answer, we repeat the same steps as we did with problem 8. Draw a vertical line through 2 on the x axis. This vertical line crosses through (2,4) on the straight part of the function, or the diagonal part of the function. The input x = 2 leads to the output y = 4. Note we can draw a horizontal line from the point until we get to 4 on the y axis.
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Problem 10.
The answer is 0 since the point (0,0) is on the function. The input x = 0 leads to y = 0 as the output. We don't need to draw any vertical line for this case since the function curve is on the x axis already.