ax^3+bx^2-5x-2可被x+1整除,说明ax^3+bx^2-5x-2有因子x+1,所以当x = -1时ax^3+bx^2-5x-2=0,
即-a + b + 5 - 2=0,
同理,当x = 2时ax^3+bx^2-5x-2=0,即8a + 4b -10 -2 =0,
整理
a - b = 3
2a + b = 3
解得a = 2,b = -1