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 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