<p>If f(x) = x+sqrt(x) and g(x) = f(f(x)), then g(4) is approximately</p>
<p>(A) 2.4
(B) 4.0
(C) 6.0
(D) 8.4
(E) 36</p>
<p>If g(x) = f(f(x)), g(4) = f(f(4)).</p>
<p>First, do f(4). This is 4+sqrt(4), which is equal to 6. Next, you have to take f(6), which is 6+sqrt(6). Without a calculator, the only answer choice that seems even remotely close to the correct one is D) 8.4, since it is greater than 6, but not by much. Using a calculator (which is allowed on the SAT) confirms this answer.</p>
<p>Ah!! Thank you! I was stuck on this problem for a long time! </p>
<p>This type of problem s very common on the SATs. Find a bunch more to practice with if you plan on taking it.</p>