If sets a and B satisfy a ∩ B = {1,2}, then different ordered set pairs (a, b) have the same property For example, the first mock exam of 2014 Shanxi province is the first one. Ask for detailed explanation
If a ∪ B = {1,2}, it is 9 pairs:
1.A={} B={1,2}
2.A={1} B={1,2}
3.A={2} B={1,2}
4.A={1,2} B={1,2}
5.A={1} B={2}
6.A={2} B={1}
7.A={1,2} B={}
8.A={1,2} B={1}
9.A={1,1} B={2}
If a + b > 0, A-B
Because a + B is greater than 0, the absolute value of positive numbers in a and B is large. Because A-B is less than 0, a is less than B, so B must be positive, so the absolute value of B is large
If a > 0, b > 0, try to compare the size of a ^ A and B ^ B,
f(x)=x^x
Let e ^ [f (x)] = Xe ^ x = g (x)
The derivative of G (x) is e ^ x + x ^ 2 * e ^ x > 0
So g (x) and f (x) increase progressively. When a > b, a ^ a > b ^ B