Câu 2 (đề 4) :
a) $x^{}$$(x-2)^{}$$-x+2^{}$$=0^{}$
$x^{}$$(x-2)^{}$$-(x-2)^{}$$=0^{}$
$(x-2)^{}$$(x+1)^{}$$=0^{}$
\(\left[ \begin{array}{l}x-2=0\\x+1=0\end{array} \right.\)
\(\left[ \begin{array}{l}x=2\\x=-1\end{array} \right.\)
b)$x^{2}$$-2x^{}$$-3^{}$$=0^{}$
$x^{2}$$-3x+x-3^{}$
${x(x-3)+(x-3)=0}$
${(x-3)(x+1)=0}$
\(\left[ \begin{array}{l}x-3=0\\x+1=0\end{array} \right.\)
\(\left[ \begin{array}{l}x=3\\x=-1\end{array} \right.\)
Đề 5:
1. Chọn D (mờ quá nên không thấy rõ lắm)
2. $x^{2}-25=0$
$x^{2}-5^{2}=0$
$(x-5)(x+5)=0$
\(\left[ \begin{array}{l}x+5=0\\x-5=0\end{array} \right.\)
\(\left[ \begin{array}{l}x=-5\\x=5\end{array} \right.\)
Có gì.. thì bạn hỏi lại nhang
