Đáp án + Giải thích các bước giải:
`1.`
`(x-2y)^2-x^2=(x-2y-x)(x-2y+x)=(-2y)(2x-2y)`
`2.`
`36x^2-(2x-3y)^2=(6x)^2-(2x-3y)^2`
`=(6x-2x+3y)(6x+2x-3y)=(4x+3y)(8x-3y)`
`3.`
`(3a+5b)^2-(a-b)^2=(3a+5b-a+b)(3a+5b+a-b)`
`=(2a+6b)(4a+4b)`
`=2(a+3b)*4(a+b)`
`=8(a+3b)(a+b)`
`4.`
`4(x-y)^2-(3x+y)^2=[2(x-y)]^2-(3x+y)^2`
`=(2x-2y)^2-(3x+y)^2`
`=(2x-2y-3x-y)(2x-2y+3x+y)`
`=(-x-3y)(5x-y)`.