Giải pt sau : x^2 – 11x – 1 = 0 gấp =((((((((((( 25/08/2021 Bởi Peyton Giải pt sau : x^2 – 11x – 1 = 0 gấp =(((((((((((
x² – 11x -1 = 0⇔ x² – 11x + $\frac{121}{4}$ – $\frac{125}{4}$ = 0⇔ ( x – $\frac{11}{2}$ ) $^{2}$ – $\frac{125}{4}$ = 0⇔ ( x – $\frac{11}{2}$ ) $^{2}$ = $\frac{125}{4}$⇔ x – $\frac{11}{2}$ = ±$\sqrt[2]{\frac{125}{4}}$⇔ x = ±$\frac{5√5}{2}$ + $\frac{11}{2}$⇔\(\left[ \begin{array}{l}x=\frac{5√5+11}{2} \\x=\frac{5√5-11}{2}\end{array} \right.\) Bình luận
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x² – 11x -1 = 0
⇔ x² – 11x + $\frac{121}{4}$ – $\frac{125}{4}$ = 0
⇔ ( x – $\frac{11}{2}$ ) $^{2}$ – $\frac{125}{4}$ = 0
⇔ ( x – $\frac{11}{2}$ ) $^{2}$ = $\frac{125}{4}$
⇔ x – $\frac{11}{2}$ = ±$\sqrt[2]{\frac{125}{4}}$
⇔ x = ±$\frac{5√5}{2}$ + $\frac{11}{2}$
⇔\(\left[ \begin{array}{l}x=\frac{5√5+11}{2} \\x=\frac{5√5-11}{2}\end{array} \right.\)