Đáp án:
Giải thích các bước giải:
$\text{Bài 1: }$
$\text{a/ (x+2y)² = x² + 2.x.2y + (2y)² = x²+4xy+4y²}$
$\text{b/ (5x + 4y)² = (5x)² + 2.5x.4y =(4y)² = 25x² +40xy+16y²}$
$\text{c/ (2x+$\frac{1}{5}$y)²= (2x)² + 2.2x.$\frac{1}{5}$y + ($\frac{1}{5}$y)² }$
$\text{= 4x² + $\frac{4}{5}$xy + $\frac{1}{25}$y² }$
$\text{Bài 2:}$
$\text{a/ x²+10x+25= x²+2.x.5+5²= (x+5)²}$
$\text{b/ 9x²+12x+4= (3x)²+2.3x.2 +2²=(3x+2)²}$
$\text{c/ x² + $\frac{2}{3}$x + $\frac{1}{9}$ }$
$\text{= x²+ 2.x.$\frac{1}{3}$ + ($\frac{1}{3}$)² = (x+$\frac{1}{3}$)² }$
$\text{Bài 3: }$
$\text{a/ (x-3y)²= x²-2.x.3y+(3y)²= x²-6xy+9y²}$
$\text{b/ (5x-y)²= (5x)²-2.5x.y+y²= 25x²-10xy+y²}$
$\text{c/ (2x-$\frac{1}{2}$y)²= (2x)²- 2.2x.$\frac{1}{2}$y+($\frac{1}{2}$y)²= 4x²-2xy+$\frac{1}{4}$y² }$
$\text{Bài 4:}$
$\text{a/ x²-8x+16= x²-2.x.4+4²= (x-4)²}$
$\text{b/ x²-12x+36= x²-2.x.6+6²= (x-6)²}$
$\text{c/ 16x²-24x+9 = (4x)²-2.4x.3+3² = (4x-3)²}$
Xin hay nhất!
