The second question is actually very simple. When you see this kind of problem, you should first check whether the formula given by the problem can be used.
F (x+3)-f (1/x) = f (x 2+3x), not used. What is needed is f (x 2+3x).
Then the title says that the function f(x) is a increasing function whose domain is on (0, positive infinity).
In fact, I want you to find out when f(y) equals 2, such as when y=m equals 2; Just y
F(y) is less than 2, x 2+3x.
In fact, the key is to find M, and it depends on whether we can find this M that makes f(m)=2 through conditions.
If f(6)= 1, find f(m)=2, which is twice the relationship.
Reverse thinking, f(x/y)=f(x)-f(y)
F(x/y)+f(y)=f(x) is deduced.
If x/y=y, it will produce the effect of 2f(y)=f(x).
That is, 2f(y)=f(x) when x = y * y
So when y=6 and x=36, f(36)=2f(6)=2.
x^2+3x-36<; 0
-3/2-√ 153/2 & lt; x & lt-3/2+√ 153/2
Then by definition, fields x+3 and 1/x are both greater than 0.
So the answer is 0.
The idea is comprehensive. Are you satisfied?
Summary of district double reduction work 1
Reducing the burden of students' homework and off-campus training in compulsory educ