如何求二次函式的對稱軸(find the axis of symmetry of a quadratic function)
什麼是二次函式(a quadratic function)？
二次多項式函式稱為二次函式。形式上，f（x）=ax2+bx+c是一個二次函式，其中a、b和c是實常數，a≠x的所有值均為0。二次函式的圖形是拋物線。
如何求二次函式的對稱軸
任何二次函式在y軸或平行於y軸的直線上顯示橫向對稱性。二次函式的對稱軸如下：
f（x）=ax2+bx+c，其中a，b，c，x∈R和a≠0
把x項寫成一個正方形，
透過重新排列上述方程的項
這意味著，對於每個可能的值f（x），都有兩個對應的x值。這可以在下麵的圖表中清楚地看到。
These values are located,
值的左右距離-b/2a。換句話說，對於任何給定的f（x），值-b/2a總是連線相應x值（點）的直線的中點。
因此，x=-b/2a是給定二次函式的對稱軸方程，形式為f（x）=ax2+bx+c
如何找到二次函式的對稱軸-示例
- 二次函式由f（x）=4x2+x+1給出。求對稱軸。
x=-b/2a=-1/（2）×4)=-1/8
因此，對稱軸的方程為x=-1/8
- 二次函式由表示式f（x）=（x-2）（2x-5）給出
透過簡化表示式，我們得到f（x）=2x2-5x-4x+10=2x2-9x+10
我們可以推匯出a=2，b=-9。因此，我們可以得到對稱軸
x=—（-9）/（2）×2)=9/4
- 發表於 2021-06-27 00:49
- 閱讀 ( 39 )
- 分類：科學
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