Câu hỏi của Yến Nhi Sky M-tp

Question

a. 3x^2-3y^2-x-y

b. 2x^2+4xy-16+2y^2

c. -x^2-x+2

d. 3x^2-7x+4

e.-2x^2+3x-1

f. x^2+2xy+y^2-2x-2y

g.x^3-2x^2+1

h.4x^2-3x-1

k. 2x^2+5x+3

l. x^2-2x-y^2+1

Trịnh Ngọc Hân · Accepted Answer

a) $3x^2-3y^2-x-y$

$\Leftrightarrow3\left(x^2-y^2\right)-x-y$

$\Leftrightarrow3\left(x-y\right)\left(x+y\right)-\left(x+y\right)$

$\Leftrightarrow3\left(x-y\right)$

d)  $3x^2-7x+4$

$\Leftrightarrow3x^2-7x+7-3$

$\Leftrightarrow\left(3x^2-3\right)-\left(7x-7\right)$

$\Leftrightarrow3\left(x^2-1\right)-7\left(x-1\right)$

$\Leftrightarrow3\left(x-1\right)\left(x+1\right)-7\left(x-1\right)$

$\Leftrightarrow\left(x-1\right)\left(3\left(x+1\right)-7\right)$

$\Leftrightarrow\left(x+1\right)\left(3x-6\right)$

e)  $-2x^2+3x-1$

$\Leftrightarrow\left(-2x^2-1^2\right)+3x$

$\Leftrightarrow\left(-2x-1\right)\left(-2x+1\right)+3x$

f)   $x^2+2xy+y^2-2x-2y$

$\Leftrightarrow\left(x+y\right)^2-2\left(x+y\right)$

k)  $2x^2+5x+3$

$\Leftrightarrow2x^2+2x+3x+3$

$\Leftrightarrow2x\left(x+1\right)+3\left(x+1\right)$

$\Leftrightarrow\left(2x+3\right)\left(x+1\right)$

l)  $x^2-2x-y^2+1$

$\Leftrightarrow\left(x^2-2x+1\right)-y^2$

$\Leftrightarrow\left(x-1\right)^2-y^2$

$\Leftrightarrow\left(x-1-y\right)\left(x-1+y\right)$Câu trả lời: a) $3x^2-3y^2-x-y$