<p>Hey,</p>
<p>I wondered about a question of CB’s official study guide.</p>
<p>It’s question 12, section 3 (1st practice test):</p>
<p>x::f(x)
:::::::
0::a
1::24
2::b</p>
<li>
The table above shows some values for the function f.
If f is a linear function, what is the value of a+b.</li>
</ol>
<p>(A) 24
(B) 36
(C) 48
(D) 72
(E) It cannot be determined from the information given.</p>
<p>The correct solution is (C). This means that f(0)+f(2) = 48. I guess, CB assumes that the equation of f is: f(x) = 24x</p>
<p>But in my opinion, answer (E) should be correct, since the equation of a linear function is: f(x) = mx + c</p>
<p>(We don’t know the constant c)</p>
<p>Can someone explain this to me?</p>
<p>Thanks in advance!</p>