Answer:
33 trees
Step-by-step explanation:
Let us assume the number of trees planed for receiving greatest yield is be x
Now the equation would be
f(x) = (21 + x) (45 - x)
= -x^2 + 24x + 945
Now we have to differentiate the f with regard to x
[tex]f^i (x) = -2x + 24\\\\f^i(x) = 0 = x = 12\\\\f^''(x) = -x (<0)[/tex]
Now as it can be seen that
f is at maximum when x = 12
So, the number of trees would be
= 21 + 12
= 33 trees