# Functions

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## 3/22 Functions

Remember to follow the Knowsys Method: Read carefully, identify the bottom line, and assess your options. After you ask, "What could I do?" and "What should I do?" attack the problem, then loop back to check whether you answered the question correctly. Finally, take a look at the answer choices and select the correct one.

The graph of y=f(x) is shown above. If $0\leq t\leq 5$, and if (t,v) is on the graph of f, which of the following must be true?

A glance at the answer choices shows that they all have v, so v=? will do for an imperfect bottom line. Now look at the question again. If t is somewhere from 0 to 5, what does that say about v? Note that t is the x value, and v is the y value, so you need to focus on the part of the graph from x=0 to x=5. In that range, the smallest y value is 5 and the greatest is 10. Now look at the answer choices.

$A) -10\leq v\leq -5$

$B)-5\leq v\leq 0$

$C) 0\leq v\leq 5$

$D) 5\leq v\leq 10$

$E)10\leq v\leq 15$

On sat.collegeboard.org, 56% of responses were correct.

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