Đáp án:
Giải thích các bước giải:
ta có:
A=$x^{2}$-9x-10=10
⇒A=$(x^{2}$-9x+$\frac{9}{2}$)^{2}$ - $\frac{121}{4}$ =10
⇒A=$(x-\frac{9}{2})^{2}$-$(√\frac{121}{4} )^{2}$=10
⇒A=(x-$\frac{9}{2}$-√$\frac{121}{4}$)(x-$\frac{9}{2}$+√$\frac{121}{4}$)=10
⇒\(\left[ \begin{array}{l}x-$\frac{9}{2}$-√$\frac{121}{4}$=2\\x-$\frac{9}{2}$+√$\frac{121}{4}$=5\end{array} \right.\)
\(\left[ \begin{array}{l}x-$\frac{9}{2}$-√$\frac{121}{4}$=5\\x-$\frac{9}{2}$+√$\frac{121}{4}$=2\end{array} \right.\)
\(\left[ \begin{array}{l}x-$\frac{9}{2}$-√$\frac{121}{4}$=10\\x-$\frac{9}{2}$+√$\frac{121}{4}$=1\end{array} \right.\)
\(\left[ \begin{array}{l}x-$\frac{9}{2}$-√$\frac{121}{4}$=1\\x-$\frac{9}{2}$+√$\frac{121}{4}$=10\end{array} \right.\)
\(\left[ \begin{array}{l}x-$\frac{9}{2}$-√$\frac{121}{4}$=-2\\x-$\frac{9}{2}$+√$\frac{121}{4}$=-5\end{array} \right.\)
\(\left[ \begin{array}{l}x-$\frac{9}{2}$-√$\frac{121}{4}$=-5\\x-$\frac{9}{2}$+√$\frac{121}{4}$=-2\end{array} \right.\)
\(\left[ \begin{array}{l}x-$\frac{9}{2}$-√$\frac{121}{4}$=-10\\x-$\frac{9}{2}$+√$\frac{121}{4}$=-1\end{array} \right.\)
\(\left[ \begin{array}{l}x-$\frac{9}{2}$-√$\frac{121}{4}$=-1\\x-$\frac{9}{2}$+√$\frac{121}{4}$=-10\end{array} \right.\)
