用完全平方公式分解因式 1+10t+25t^2 m^2-14m+49 y^2+y+1/4 (m+n)^2-4m(m+n)+4m^2 25a^2-80a+64a^2+2a(b+c)+(b+c)^2
问题描述：
用完全平方公式分解因式 1+10t+25t^2 m^2-14m+49 y^2+y+1/4 (m+n)^2-4m(m+n)+4m^2 25a^2-80a+64
a^2+2a(b+c)+(b+c)^2
答
1+10t+25t^2
=(1+5t)^2
m^2-14m+49
=(m-7)^2
y^2+y+1/4
=(y+1/2)^2
(m+n)^2-4m(m+n)+4m^2
=[(m+n)-2m]^2
=(n-m)^2
25a^2-80a+64
=(5a-8)^2
a^2+2a(b+c)+(b+c)^2
=[a+(b+c)]^2
=(a+b+c)^2