(1)x²-9x+_81/4___=_____（x-9/2）²_____
(2)a^4+10a²+__25__=___(a²+5)²_______
(3)-__4n+1______+4n²=____(_2n-1)_²_______
(4)4x²+___20xy__+25y²=____(2x+5y)²_______
(5)9a²b²+15ab+__25/4___=_(3ab+5/2)²_______
(6)x^4+x²+__1/4____=____(x²+1/2)²_____
分解因式
(1)a²-6ab+9b²=______(a-3b)²_______
(2)16+24m+9m²=____(3m+4)²____________
(3)a²b²-ab+¼=_______(ab-1/2)²_____
(4)49x²-14xy+y²=______(7x-y)²______
(5)1/9+1/3x²+1/4x^4=___(1/2x²+1/3)²_________
(6)25a²-20ab+4b²=________(5a-2b)²_____