Đáp án+Giải thích các bước giải:
1) $x^{2}$ - 6x + 9
= $x^{2}$ - 2.3.x + $3^{2}$
= $(x-3)^{2}$
2)25+10x+ $x^{2}$
=$5^{2}$+2.5.x+ $x^{2}$
=$(5+x)^{2}$
3)$x^{3}$-$3x^{2}$+3x-1
=($x^{3}$-1)-($3x^{2}$-3x)
=(x-1)($x^{2}$+x+1)-3x(x-1)
=(x-1)($x^{2}$+x+1-3x)
=(x-1)($(x-2)^{2}$)
4)$x^{3}$+$6x^{2}$+12x+8
=($x^{3}$+$2^{3}$)+($6x^{2}$+12x)
=(x+2)($x^{2}$+2x+4)+6x(x+2)
=(x+2)($x^{2}$+12x+4)
5)$x^{3}$-$8y^{3}$
=$x^{3}$-($(2y)^{3}$)
9=(x-2y)($x^{2}$-2xy+$4y^{2}$)
6)$(3x+2)^{2}$-4
=$(3x+2)^{2}$-$2^{2}$
=3x(3x+4)
7)$4x^{2}$-$25y^{2}$
=(2x-5y)(2x+5y)
8)$125x^{3}$-$64y^{3}$
=(5x-4y)($25x^{2}$+20xy+$16y^{2}$)
9)$(x-3)^{3}$-$(x+3)^{3}$
=(x-3-x-3)($(x-3)^{2}$+$x^{2}$-9+$(x+3)^{2}$)
=0
10)$y^{4}$-$14y^{2}$+49
=$($y^2$)^{2}$-2.7.$y^{2}$+$7^{2}$
=($y^{2}$-7)^2
