八年级上册数学书171页第三题

1) 1+10t+25t^2=(5t)^2+2*5t*1+1^2=(5t+1)^22) m^2-14m+49=m^2-2*m*7+7^2=(m-7)^23) y^2+y1/4=y^2+2*y*1/2+(1/2)^2=(y+1/2)^24) (m+n)^2-4m(m+n)+4m^2=(2m)^2-2*2m*(m+n)+(m+n)^2=(2m-(m+n))^2=(m-n)^25) 25a^2-80a+...