导数表示函数在某一点的瞬时变化率,几何上是切线的斜率。
| 分组 | 函数 | 导数 | 示例(代入数字算一算) |
|---|---|---|---|
| 常数函数 | y = C | 0 | 如 y = 5 ⟹ y′ =0,x 取几都一样 |
| 幂函数 | y = xμ | μ·xμ−1 | 如 y = x²,x = 3 ⟹ y′ = 2×3 =6;√x、1/x 也都是它 |
| 指数函数 | y = ax (a>0, a≠1) | ax · ln a | 如 y = 2x,x = 1 ⟹ y′ = 2×ln2 ≈1.39 |
| y = ex | ex | 如 x = 2 ⟹ y′ = e² ≈7.39(导数永远是它自己) | |
| 对数函数 | y = loga x | 1x · ln a | 如 y = log₂x,x = 4 ⟹ y′ = 1/(4×0.693) ≈0.36 |
| y = ln x | 1x | 如 x = 1 ⟹ y′ = 1/1 =1 | |
| 三角函数 | y = sin x | cos x | 如 x = π/3(60°)⟹ y′ = cos60° =0.5 |
| y = cos x | −sin x | 如 x = π/3 ⟹ y′ = −sin60° ≈−0.87 | |
| y = tan x | sec2x = 1cos2x | 如 x = π/4(45°)⟹ y′ = 1/cos²45° =2 | |
| y = cot x | −csc2x = −1sin2x | 如 x = π/4 ⟹ y′ = −1/sin²45° =−2 | |
| 反三角函数 | y = arcsin x | 1√(1 − x2) | 如 x = 0 ⟹ y′ =1;x = 0.5 ⟹ 2/√3 ≈1.15 |
| y = arccos x | −1√(1 − x2) | 如 x = 0.5 ⟹ y′ ≈−1.15 | |
| y = arctan x | 11 + x2 | 如 x = 1 ⟹ y′ = 1/(1+1) =0.5 | |
| y = arccot x | −11 + x2 | 如 x = 1 ⟹ y′ =−0.5 |