f(x) = 2x⁴ - 16x²
f'(x) = 2(x⁴)' - 16(x²)' = 8x³ - 32x
f'(x) ≥ 0
8x³ - 32x ≥ 0
8x(x² - 4) ≥ 0
x(x - 2)(x + 2) ≥ 0
- + - +
[- 2][0][2]
x ∈ [- 2 ; 0] ∪ [2 ; + ∞)
f(x) = 2x⁴ - 16x²
f'(x) = 2(x⁴)' - 16(x²)' = 8x³ - 32x
f'(x) ≥ 0
8x³ - 32x ≥ 0
8x(x² - 4) ≥ 0
x(x - 2)(x + 2) ≥ 0
- + - +
[- 2][0][2]
x ∈ [- 2 ; 0] ∪ [2 ; + ∞)