Đáp án_Giải thích các bước giải:
Bài 1:
`a)` `(x+1)^2=x^2+2*x*1+1^2=x^2+2x+1`
`b)` `(2x+y)^2=(2x)^2+2*2x*y+y^2=4x^2+4xy+y^2`
`c)` `(3x-2y)^2=(3x)^2-2*3x*2y+(2y)^2=9x^2-12xy+4y^2`
`d)` `(x-2)^2=x^2-2*x*2+2^2=x^2-4x+4`
`e)` `(5x-1/2y)^2=(5x)^2-2*5x*1/2y+(1/2y)^2=25x^2-5xy+1/4y^2`
`f)` `(x+2y)(x-2y)=x^2-(2y)^2=x^2-4y^2`
`g)` `(3x+5)^2=(3x)^2+2*3x*5+5^2=9x^2+30x+25`
`h)` `(5x-3)(5x+3)=(5x)^2-3^2=25x^2-9`
`i)` `(6x+5y)(6x-5y)=(6x)^2-(5y)^2=36x^2-25y^2`
Bài 2:
`a)` `(2x-y)^2=(2x)^2-2*2x*y+y^2=4x^2-4xy+y^2`
`b)` `(2x^2y-z)^2=(2x^2y)^2-2*2x^2y*z+z^2=4x^4y-4x^2yz+z^2`
`c)` `(x+1/2y)^2=x^2+2*x*1/2y+(1/2y)^2=x^2+xy+1/4y^2`
`d)` `(x-2y)(2y+x)=x^2-(2y)^2=x^2-4y^2`
`e)` `(2x+5y)^2=(2x)^2+2*2x*5y+(5y)^2=4x^2+20xy+25y^2`
`f)` `(3x-y)^2=(3x)^2-2*3x*y+y^2=9x^2-6xy+y^2`
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