填充第8題
題目應是相異實根的個數吧?
\(f'\left( x \right)=3{{x}^{2}}+2ax+b=0\)之兩根為\({{x}_{1}},{{x}_{2}}\)
\(3{{\left[ f\left( x \right) \right]}^{2}}+2af\left( x \right)+b=0\)之根為\(f\left( x \right)={{x}_{1}}\)或\(f\left( x \right)={{x}_{2}}\)的根
畫圖可知\(f\left( x \right)={{x}_{1}}\)有兩相異實根,\(f\left( x \right)={{x}_{2}}\)有一根
故\(3{{\left[ f\left( x \right) \right]}^{2}}+2af\left( x \right)+b=0\)的相異實根個數為3 作者: thepiano 時間: 2020-6-19 11:49 標題: 回復 5# Superconan 的帖子