Đáp án:
Giải thích các bước giải:
a)(3b+5a/6)^2=(3b)^2+2.(3b).(5a/6)+(5a/2)=9b^2+5ab+25a^2/36
b)(5x-y)^2=(5x)^2.(5x)y+y^2=25x^2-10xy+y^2
2.a)(x+1/4)^2=x^2+1/2x+1/16
b)(4x/5+7y/10)(7y/10-4x/5)=(7y/10)^2-(4x/5)^2=49y^2/100-16x^2/25
3.a^2-6a+9=a^2-2.3.a+(3)^2=(a-3)^2
b)=(1/2x)^2+2.(1/2x).(2y^2)+(2y^2)^2=(1/2x+2y^2)
4.2001^2=(2000+1)^2=(2000)^2+2.2000.1+1^2=4000000+4000+1=4004001
1999^2=(2000-1)^2=2000^2-2.2000.1+1^2=4000000-4000+1=3996001
c)57.63=(60-3)*(60+3)=3600-9=3591
a=2012.2014=(2013-1).(2013+1)=2013^2-1<2013^2
Vậy a<b
