解
(1)1+10t+25t^2
=1²+2×5t+(5t)²
=(1+5t)²
(2)m^2-14m+49
=m²-2×7m+7²
=(m-7)²
(3)y^2+y+4/1(四分之一)
=y²+1/2×2y+(1/2)²
=(y+1/2)²
(4)(m+n)^2-4m(m+n)+4m^2
=(m+n)²-(m+n)×2×2m+(2m)²
=[(m+n)-2m]²
=(n-m)²
(5)25a^2-80a+64
=(5a)²-5a×2×8+8²
=(5a-8)²
(6)a^2+2a(b+c)+(b+c)^2
=a²+2a×(b+c)+(b+c)²
=[a+(b+c)]²
=(a+b+c)²
(7)(a-b)^2+4ab
=a²-2ab+b²+4ab
=a²+2ab+b²
=(a+b)²
(8)(p-4)(p+1)+3p
=p²-3p-4+3p
=p²-4
=(p-2)(p+2)
(9)4xy^2-4x^2y-y^3
=-y(y²-4xy+4x²)
=-y(y-2x)²
(10)3ax^2-3ay^2
=3a(x²-y²)
=3a(x-y)(x+y)