2（3a+5)=-2（2a-3)
6a+10=-4a+6
6a+4a=6-10
10a=-4
5a=-2
a=-2/5
a的2次方+5a+1
=(-2/5)的2次方+5*(-2/5)+1
=4/25-2+1
=4/25-1
=-21/25