－化简求值2／3a-{1／3－[(3a²-5a+1)]},其中a=3
问题描述：
－化简求值2／3a-{1／3－[(3a²-5a+1)]},其中a=3
答
(3a平方+6a-1)+(2-5a+a的平方)-(1-a-4a平方)
=3a平方+6a-1+2-5a+a的平方-1+a+4a平方
=8a平方+2a
=8*(1/9)+2*(1/3)
=14/9
答
2／3a-{1／3-[(3a²-5a+1)]}
=2／3a-{1／3-3a²+5a-1}
=2／3a-1／3+3a²-5a+1
=3a²+2／3a-5a-1／3+1
=3a²-13／3a+2／3
=3*3²-13／3*3+2／3
=27-13+2/3
=14+2/3
=46/3