八年级上册数学书171页第三题
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八年级上册数学书171页第三题
![八年级上册数学书171页第三题](/uploads/image/z/15137870-14-0.jpg?t=%E5%85%AB%E5%B9%B4%E7%BA%A7%E4%B8%8A%E5%86%8C%E6%95%B0%E5%AD%A6%E4%B9%A6171%E9%A1%B5%E7%AC%AC%E4%B8%89%E9%A2%98)
1) 1+10t+25t^2
=(5t)^2+2*5t*1+1^2
=(5t+1)^2
2) m^2-14m+49
=m^2-2*m*7+7^2
=(m-7)^2
3) y^2+y1/4
=y^2+2*y*1/2+(1/2)^2
=(y+1/2)^2
4) (m+n)^2-4m(m+n)+4m^2
=(2m)^2-2*2m*(m+n)+(m+n)^2
=(2m-(m+n))^2
=(m-n)^2
5) 25a^2-80a+64
=(5a)^2-2*5a*8+8^2
=(5a-8)^2
6) a^2+2a(b+c)+(b+c)^2
=a^2+2*a*(b+c)+(b+c)^2
=(a+b+c)^2
=(5t)^2+2*5t*1+1^2
=(5t+1)^2
2) m^2-14m+49
=m^2-2*m*7+7^2
=(m-7)^2
3) y^2+y1/4
=y^2+2*y*1/2+(1/2)^2
=(y+1/2)^2
4) (m+n)^2-4m(m+n)+4m^2
=(2m)^2-2*2m*(m+n)+(m+n)^2
=(2m-(m+n))^2
=(m-n)^2
5) 25a^2-80a+64
=(5a)^2-2*5a*8+8^2
=(5a-8)^2
6) a^2+2a(b+c)+(b+c)^2
=a^2+2*a*(b+c)+(b+c)^2
=(a+b+c)^2