Chọn  câu sai.

$\left( {5x - 2y} \right)\left( {x + 4y} \right)$           

$\left( {5x + 4} \right)\left( {x - 2y} \right)$

$\left( {x + 2y} \right)\left( {5x - 4} \right)$

$\left( {5x - 4} \right)\left( {x - 2y} \right)$

$\left( {{a^2} + b} \right)\left( {5x - 2y} \right)$.

$\left( {{a^2} - b} \right)\left( {2x - 5y} \right)$.

$\left( {{a^2} + b} \right)\left( {2x + 5y} \right)$.

$\left( {{a^2} + b} \right)\left( {2x - 5y} \right)$.

$\left( {x + y + 2xy} \right)$ 

$\left( {x - y + 2xy} \right)$  

$\left( {x - y + xy} \right)$

$\left( {x - y + 3xy} \right)$

$2{a^2}{c^2} - 2abc + bd - acd = \left( {2ac - d} \right)\left( {ac - b} \right)$.     

$2{a^2}{c^2} - 2abc + bd - acd = \left( {2ac - d} \right)\left( {ac + b} \right)$.

$2{a^2}{c^2} - 2abc + bd - acd = \left( {2ac + d} \right)\left( {ac - b} \right)$.    

$2{a^2}{c^2} - 2abc + bd - acd = \left( {2ac + d} \right)\left( {ac + b} \right)$.

$m = 5;\,n =  - 1$.

$m =  - 5;\,n =  - 1$.

$m = 5;\,n = 1$.

$m =  - 5;\,n = 1$.

$m < 0$.

$1 < m < 3$.

$2 < m < 4$.

$m > 4$.