Cho biểu thức $M = {x^2}\left( {3x - 2} \right) + x\left( { - 3{x^2} + 1} \right).$ Hãy chọn câu đúng:

${\left( {x + y} \right)^2} = \left( {x + y} \right)\left( {x + y} \right)$.

${x^2} - {y^2} = \left( {x + y} \right)\left( {x - y} \right)$.

 ${\left( { - x - y} \right)^2} = {\left( { - x} \right)^2} - 2\left( { - x} \right)y + {y^2}$.

$\left( {x + y} \right)\left( {x + y} \right) = {y^2} - {x^2}$.

$4 - {\left( {a + b} \right)^2} = \left( {2 + a + b} \right)\left( {2 - a + b} \right)$.

$4 - {\left( {a + b} \right)^2} = \left( {4 + a + b} \right)\left( {4 - a - b} \right)$.

$4 - {\left( {a + b} \right)^2} = \left( {2 + a - b} \right)\left( {2 - a + b} \right)$.

$4 - {\left( {a + b} \right)^2} = \left( {2 + a + b} \right)\left( {2 - a - b} \right)$.

$8$

$- 8$

$6$

$- 6$

$- 15x + 1$

$1$

$15x + 1$

$- 1$

$\left( {x + a} \right)\left( {x + b} \right) = {x^2} + mx + n$

$\left( {x + a} \right)\left( {x + b} \right) = {x^2} + nx + m$

$\left( {x + a} \right)\left( {x + b} \right) = {x^2} - mx - n$

$\left( {x + a} \right)\left( {x + b} \right) = {x^2} - mx + n$

$2{y^{2n}}$

$- 5$

${x^{2n}}$

$5$