260109-test

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严浩
2026-01-09 17:01:17 +08:00
parent 888a6d5a24
commit 97154d4b5b
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# /// script
# requires-python = ">=3.11"
# dependencies = ["sympy"]
# ///
import sympy as sp
# 定义符号(实数)
x = sp.symbols("x", real=True)
# 定义函数
y = -2 * x**2 + 8 * x - 3
# 方法1通过顶点公式求解
# 二次函数 y = ax^2 + bx + c 的顶点公式x = -b/(2a)
a = -2
b = 8
c = -3
x_vertex = -b / (2 * a)
y_vertex = a * x_vertex**2 + b * x_vertex + c
# 方法2通过求导验证
dy_dx = sp.diff(y, x)
critical_points = sp.solve(dy_dx, x)
d2y_dx2 = sp.diff(dy_dx, x)
print("=" * 50)
print("二次函数y = -2x² + 8x - 3")
print("=" * 50)
print("\n【方法1顶点公式】")
print(f"顶点坐标:({x_vertex}, {y_vertex})")
print("\n【方法2求导法】")
print(f"导数y' = {dy_dx}")
print(f"二阶导数y'' = {d2y_dx2}")
print(f"临界点x = {critical_points[0]}")
print(f"代入原函数y = {y.subs(x, critical_points[0])}")
print(f"二阶导数:{d2y_dx2} < 0故为极大值点")
print("\n【结论】")
print(f"1. 顶点坐标:({x_vertex}, {y_vertex})")
print(f"2. 函数最大值:{y_vertex}")