Đáp án:
`1) a)` `x^2 + 20x + 100 = (x+10)^2`
b) `16x^2 + 24xy + 9y^2 = (4x+3y)^2`
c) `y^2-14x+49 = (y-7)^2`
d) `9x^2 - 42xy + 49y^2 = (3x-7y)^2`
------------------------------------------------------------------------------------
2) a) `4x^2 - 9y^2 = (2x-3y)(2x+3y)`
b) `16-x^2 = (4-x)(4+x)`
c) `49x^2 - 1 = (7x-1)(7x+1)`
d) `16x^2 - 25 = (4x-5)(4x+5)`
------------------------------------------------------------------------------------
3) a) `8x^3 + 36x^2y+54xy^2+27y^3 = (2x+3y)^3`
b) `x^3 - 6x^2y + 12xy^2 - 8y^3 = (x-2y)^3`
c) `(2a+3b)(4a^2-6ab+9b^2)=8a^3+27b^2`
d) `(3x-4y)(9x^2+12xy+16y^2)=27x^3-64y^3`
