SAT Math Question Help Please?

<p>17) If f(x)=x-k where k is a constant, and the points (6,1) and (8,1) lie on the graph of y=f(x), what is the value of f(0)?</p>

<p>This is a grid-in question. I have no idea about how to do this question, except that f(x)=1. My book's explanation says, ''f(x)=y=lx-kl'', but I don't understand why the absolute value things are there. </p>

<p>Help??</p>

<p>The graph of f(x) is a horizontal line. The slope is 0. Therefore, y value will never change. f(0) is 1.</p>

<p>f(100) is 1 as well
f(-100000000) is 1.</p>

<p>The question must be written wrong!</p>

<p>You are given that f(6)=1 and f(8)=1</p>

<p>f(6)=1 implies that 1=6-k, or k=5
f(8)=1 implies that 1=8-k, or k=7.</p>

<p>But k can’t be both 5 and 7.</p>

<p>Sooooo…I’m guessing that the question is supposed to say f(x)=|x-k|.
This DOES give that k=7 (see if you can show why).</p>

<p>So f(x)=|x-7|, and f(0)=|-7|=7.</p>

<p>Remark: The graph of the function f(x)=|x-7| is NOT a line. It looks like a V, with the “vertex” of the V at the point (7,0).</p>

<p>Thanks, but I still don’t understand why there are l l’s around x-7.</p>

<p>There’s a typo in the book. The only way the question makes sense is if the question was:</p>

<p>17) If f(x)=|x-k| where k is a constant …</p>

<p>Are you saying that you don’t understand the definition of absolute value?</p>

<p>Seems like :D</p>

<p>[SAT:</a> Improve SAT Score with SparkNotes: Algebra, ABSOLUTE Value, and Exponents](<a href=“SparkNotes: Today's Most Popular Study Guides”>SparkNotes: Today's Most Popular Study Guides)</p>

<p>There you go, a brief explanation of absolute value</p>