Đáp án:
:))
Giải thích các bước giải:
1) $x^{2}$ - 7x = x ( x- 7)
2)$x^{2}$ - 5x - 24 = $x^{2}$ + 8x - 3x - 24 = x(x+8) - 3(x+8) = (x+8)(x-3)
3) $x^{2}$ + 8x + 16 = $(x+4)^{2}$
4) $4x^{4}$ + $20x^{2}$ +25 = $(2x)^{2}$ + 2.2$x^{2}$.5+ $5^{2}$ = ($2x^{2}$ + 5 ) ²
5) $5x^{2}$ +10xy + $5y^{2}$ = 5 ( $x^{2}$ + 2xy + $y^{2}$ ) = 5 ( x+ y) ²
6) $2x^{3}$ +$8x^{2}$ +8x = 2x ( $x^{2}$ +4x + 4 ) = 2x (x+ 2) ²
8) $5x^{2}$ - 20 = 5 ( x ²- 4 ) = 5 ( x- 2)(x + 2)
7) $x^{2}$ - 2x + 1 - $y^{2}$ - 2y - 1 = $(x+1)^{2}$ - $(y+1)^{2}$ = ( x+1-y-1)(x+1+y+1)=(x-y)(x+y+2)
9) $2x^{2}$ - 3x -2 = $2x^{2}$ - 4x + x - 2 = 2x ( x- 2 ) + (x - 2) = (2x+1)(x-2)
10) $6x^{2}$ + 7x - 3 = $6x^{2}$ -2x + 9x - 3 = 2x ( 3x - 1 ) + 3 ( 3x -1 ) = (3x - 1) ( 2x + 3)
