x=-2时 y = ax^5 + bx³+cx-1 = 5
即 a(-2)^5+b(-2)³+c(-2) = 6
即 a*2^5 + b*2³ + c*2 = -6
当 x=-2时 y = a*2^5 + b*2³ + c*2 -1 = -6-1 =-7