Chọn câu sai. Với đa thức \(B \ne 0\) ta có

\(\dfrac{{x - y}}{{5(x + y)}}\)

\(\dfrac{{5(x - y)}}{{x + y}}\)

\(\dfrac{{5{{(x - y)}^2}}}{{x + y}}\)

\(\dfrac{5}{{x + y}}\)

\(x \ne 8\).

\(x \ne 4\) và \(\,x \ne  - 4\).

\(x \ne  - 4\).

\(x \ne 4\).

$a - b - c$

$a + b + c$

$a - b + c$

$a + b - c$

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

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

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

${\left( {x - 2} \right)^2}$

\(A = {x^2} + 2x - 3\)

\(A = {x^2} + 2x + 3\)

\(A = {x^2} - 2x - 3\)

\(A = {x^2} + 2x\)

$\dfrac{{\left( {{a^2} + {b^2}} \right)\left( {a + b} \right)}}{{a - b}}$

$\dfrac{{{a^2} + {b^2}}}{{a - b}}$

${\left( {{a^2} + {b^2}} \right)^2}\left( {a + b} \right)^2$

$\left( {{a^2} + {b^2}} \right)\left( {a + b} \right)$