<p>hey,</p>
<p>so can anyone clear up question 12 on page 398 of the blue book for me</p>
<p>it was solved here already with an explanatino:
<a href="http://talk.collegeconfidential.com/sat-act-tests-test-preparation/112708-math-sat-i-question-help.html%5B/url%5D">http://talk.collegeconfidential.com/sat-act-tests-test-preparation/112708-math-sat-i-question-help.html</a></p>
<p>but for some reason i just cant really grasp the explanation</p>
<p>Since the function is linear, you can find the values of a and b by setting up proportions.</p>
<p>i got c for an answer and it was correct:</p>
<p>it’s linear. Therefor, there must be a relation between a, 24, and b. </p>
<p>Now, if f(1) = 24,
then f(0) = a. ----> from that: a = 24 * 0 = 24.</p>
<p>same for b: </p>
<p>if f(1)= 24 then b = 2 * 24 = 48</p>
<p>the sum of both b and a is= 48 (C)</p>
<p>really sorry, am bad in explaining such things X</p>
<p>0,1,2 is the dead giveaway that it’s a linear function (or graph if you want to think in that terminology).</p>
<p>You know it’s linear.</p>
<p>Because of this, a and b are going to be equidistant from 24. In other words, the average of a and b is 24. Mathematically:</p>
<p>(a + b)/2 = 24
a + b = 48</p>
<p>If what you can’t grasp is the debate between what a linear function actually is (regarding what the y-intercept is), don’t worry about that. </p>
<p>Basically, a linear function will be a straight line that isn’t vertical. I’d recommend to draw some straight lines that go through (1,24). You should soon recognize that the y values at 0 and 2 add up to 48 (or at least recognize that they’ll add up to a constant). A horizontal line will be 24+24. A line going through the origin will be 0+48. A line going through a y-int of 1 will be 1+47. Jamesford shows the math behind this.</p>