举报
carst
1. f ‘(x)=e^x+4x-3 , 斜率 f’(1)=e+1 切线 y-(e-1)=(e+1)(x-1) 即 y = (e+1)x -2 2. e^x+2x^2 -3x ≥ 5x²/2+(a-3)x+1 令 g(x)= e^x+2x^2 -3x - { 5x²/2+(a-3)x+1 } , g’(x)= e^x - x – a , g”(x)=e^x – 1 ≥0 即 当x≥1/2 时,g(x)= e^x - x²/2 – ax -1≥0 g(1/2)= √e -9/8-a/2 ≥0 => a≤2√e - 9/4 ① g’(1/2) = √e - 1/2 – a ≥0 => a≤√e – 1/2 ② 由①、②得:a≤√e – 1/2