Đáp án:
Giải thích các bước giải:
$\text{3)(x²+5x+25)(x-5)-x(x+1)}$
$\text{⇔(x-5)(x²+5x+25)-x²-1}$
$\text{⇔x³-5³-x²-x}$
$\text{⇔x³-x²-x-125}$
$\text{4)(x-1)³-3(x+2)}$
$\text{⇔x³-3x²+3x-1-3x-6}$
$\text{x³-3x²-7}$
$\text{5)(x+2)³-(x+3)(x-3)}$
$\text{⇔x³+6x²+12x+8-x²-9}$
$\text{⇔x³+5x²+12x-1}$
$\text{6)(3-2x)³-(x-5)(x+5)}$
$\text{⇔27-54x+36x²-8x³-x²+25}$
$\text{⇔-8x³+35x²-54x+52}$
$\text{6)(x+1)(x²-x+1)-(x³-9x²)}$
$\text{⇔x³-1-x³+9x²}$
$\text{⇔9x²-1}$
$\text{⇔(3x)²-1}$
$\text{⇔(3x-1)(3x+1)}$
