2个回答
（2x-y-3)^2
=[(2x-y)-3]^2
=(2x-y)^2-6(2x-y)+9
=4x^2-4xy+y^2-12x+6y+9
(x+y+1)(x+y-1)
=[(x+y)+1][(x+y)-1]
=(x+y)^2-1
=x^2+2xy+y^2-1
不是3的倍数平方+1，3的倍数平方-2
5=2^2+1
7=3^2-2
17=4^2+1
26=5^2+1
?=6^2-2=34
50=7^2+1
?=8^2+1=65
79=9^2-2
101=10^2+1
所以括号里填34 65