当x=4时,多项式A=ax平方-4X-6a的值是-1
a*4^2-4*4-6a=-1
16a-16-6a=-1
a=17/10
x=5时,
A=ax平方-4X-6a
=17/10*5^2-4*5-6*17/10
=85/2-20-51/5
=45/2-51/5
=22.5-10.2
=12.3