SAT composite functions problem: don't understand

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1

<h2>x f(x)</h2>

<p>2 -1
3 0
4 2
5 -3
6 4
7 -5
8 6</p>

<p>Several values of the function f are shown above. The function g is defined by g(x) = f(3x + 1). What is the value of g(2)? </p>

<p>I understand that this is a composite function problem. I know that the first step is to solve f(3x+1). Therefore, I have f(7).</p>

<p>But when I come to work on g(7), it doesn't make sense to me to look at the value 7 in the "x" column and match it wish -5 in the "f(x)" column.
The way I understand it, solving g(7) must come from the f(x) column.<br>
Could you explain how this second step works? What's the purpose of the x column?</p>

<p>The answer is -5, but I don't get the second step, when it comes to solving for g.</p>

2

<p>G(x)=f(3x+1)
G(2)=f(3x2+1)=f(6+1)=F(7)
u see g(2)=f(7) since f(7)=-5 g(2)=-5
get it? g(2)=f(7)=-5
problem asks you to find g(2) not g(7)</p>

3

<p>i think you misunderstood first column of this</p>

<h2>x f(x)</h2>

<p>2 -1
3 0
4 2
5 -3
6 4
7 -5
8 6</p>

<p>first X is value of X , second values of this column under f(x) shows solution to function
u see
f(x)
f(2)=-1
f(3)=0
f(4)=2
…
f(7)=-5
Hope this helps</p>

4

<p>thanks. I made headway with that</p>