Question

Answer 1

Câu 13:

a. $3(x-y)=3x-3y$

b. $(x+5)(y-4)=xy-4x+5y-20$

c. $(25x^5-5x^4+10x^2): (5x^2)=5x^2(5x^3-x^2+2x): (5x^2)$

$=5x^3-x^2+2x$

 

Answer 2

Câu 14:

a. $5xy+10y=5y(x+2)$
b. $2x-2y-x^2+2xy-y^2=(2x-2y)-(x^2-2xy+y^2)$

$=2(x-y)-(x-y)^2=(x-y)(2-x+y)$

c.

$x^3+4x^2+4x-xy^2=x(x^2+4x+4-y^2)$

$=x[(x^2+4x+4)-y^2]=x[(x+2)^2-y^2]=x(x+2-y)(x+2+y)$

d.

$x^2-4x=0$

$\Leftrightarrow x(x-4)=0$

$\Rightarrow x=0$ hoặc $x=4$