We have to functions, namely:
![f(x)=200(2)^(x) \ and \ g(x)=500x+400](https://img.qammunity.org/2019/formulas/mathematics/high-school/tuk3ez5oobr83g5kql9som8rsf56cp9vwj.png)
So the problem is asking for the smallest positive integer for
![x](https://img.qammunity.org/2019/formulas/mathematics/college/lhtxftojjkzsmo3o2h4ilq8naohracejui.png)
so that
![f(x)](https://img.qammunity.org/2019/formulas/mathematics/high-school/dcofkcfwvli28hxbmh7qv2dr7hnzsu78mx.png)
is greater than the value of
![g(x)](https://img.qammunity.org/2019/formulas/mathematics/high-school/mi01gpstrsnoqgaf67hp58q3i2kcs4n2q4.png)
, that is:
![f(x)\ \textgreater \ g(x) \\ \therefore 200(2)^(x)\ \textgreater \ 500x+400](https://img.qammunity.org/2019/formulas/mathematics/high-school/sir8o4tqpwl6bb7cz6hf6vvt4ppuj9uw1j.png)
Let's solve this problem by using the trial and error method:
![for \ x=1 \\f(1)=400 \\ g(1)=900 \\ Then \ f(1) \ \textless \ g(1) \\ \\ \\ for \ x=2 \\f(2)=800 \\ g(2)=1400\\ Then \ f(2)\ \textless \ g(2) \\ \\ \\ for \ x=3 \\f(3)=1600 \\ g(3)=1900 \\ Then \ f(3)\ \textless \ g(3) \\ \\ \\ for \ x=4 \\f(4)=3200 \\ g(4)=2400 \\ \boxed{Then \ f(4)\ \textgreater \ g(4)}](https://img.qammunity.org/2019/formulas/mathematics/high-school/vbsszh1gviq0qcsag613r1fx04xbf4m1p9.png)
So starting
![x](https://img.qammunity.org/2019/formulas/mathematics/college/lhtxftojjkzsmo3o2h4ilq8naohracejui.png)
from 1 and increasing it in steps of one we find that:
![f(x)>g(x)](https://img.qammunity.org/2019/formulas/mathematics/high-school/xbs17qp3d0ho5y1nw8q02deqdhqmp0xl76.png)
when
![x=4](https://img.qammunity.org/2019/formulas/mathematics/middle-school/i23qk0uwhi1ehnolmndlq35wd5e9sddv2g.png)
That is,
the smallest positive integer for
![x](https://img.qammunity.org/2019/formulas/mathematics/college/lhtxftojjkzsmo3o2h4ilq8naohracejui.png)
so that the function
![f(x)](https://img.qammunity.org/2019/formulas/mathematics/high-school/dcofkcfwvli28hxbmh7qv2dr7hnzsu78mx.png)
is greater than
is 4.