113 中山女中
版主: thepiano
Re: 113 中山女中
第 7 題
令 f(x) = ka^x
f(x + y) = 2f(x)f(y)
ka^(x + y) = 2 * ka^x * ka^y
k = 1/2
f(x) = (1/2)a^x
f'(x) = (lna/2)a^x
f'(0) = 2，lna = 4
f''(x)/f(x) = [(1/2)(lna)^2 * a^x]/[(1/2)a^x] = 16
令 f(x) = ka^x
f(x + y) = 2f(x)f(y)
ka^(x + y) = 2 * ka^x * ka^y
k = 1/2
f(x) = (1/2)a^x
f'(x) = (lna/2)a^x
f'(0) = 2，lna = 4
f''(x)/f(x) = [(1/2)(lna)^2 * a^x]/[(1/2)a^x] = 16