$\text{_Bài làm_}$
$\text{Bài 1: Tính}$
$\text{a) (2x+3)² = (2x)²+2.2x.3+3² = 4x²+12x+9}$
$\text{b) (3x-5y)² = (3x)²-2.3x.5y+(5y)² = 9x²-30xy+25y²}$
$\text{c) Đề sai sai!!!}$
$\text{d) 8x³+1 = (2x)³+1³ = (2x+1)[(2x)²+2x.1+1²] = (2x+1)(4x²+2x+1)}$
$\text{Bài 2: Áp dụng tính:}$
$\text{a) 3x(x²-5x+$\frac{1}{3}$)}$ = 3x³-15x²+1x}$
$\text{b) (2x-5)(x²-3x+4) = 2x³-6x²+8x-5x²+15x-20 = 2x³-11x²+23x-20}$
$\text{Hc tốt!!!}$
