1、
设f(x) = x^a,g(x) = x^b
4 = 2^a,4 = (1/2)^b = 1/2^b
a = log_2(4) = 2,b = log_(1/2)(4) = - 2
f(x) = x²
g(x) = x^(- 2) = 1/x²
1、(1)
f(x) > g(x)
x² > 1/x²
x⁴ - 1 > 0
(x - 1)(x + 1) > 0
x < - 1 或 x > 1
2、(2)
f(x) = g(x)
x² = 1/x²
x⁴ = 1
x = 1 或 x = - 1
2、(3)
f(x) < g(x)
x² < 1/x²
x⁴ - 1 < 0
(x - 1)(x + 1) < 0
- 1 < x < 1,∵x ≠ 0,∴
- 1 < x < 0 或 0 < x < 1