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歡迎您訪問數學考題練習:x2+4x-12=0(用配方法)!

數學考題練習:x2+4x-12=0(用配方法)

更新時間:2024-01-12 16:34:11作者:貝語網校

x2+4x-12=0(用配方法)

試題答案

解:移項,得

x2+4x=12,

等式兩邊同時加上一次項系數一半的平4,得

x2+4x+4=16,

∴(x+2)2=16

∴x+2=±4,

∴x1=2,x2=-6.

試題解析

配方法的一般步驟:

(1)把常數項移到等號的右邊;

(2)把二次項的系數化為1;

(3)等式兩邊同時加上一次項系數一半的平方.

點評:此題考查了配方法解一元二次方程,解題時要注意解題步驟的準確應用.選擇用配方法解一元二次方程時,最好使方程的二次項的系數為1,一次項的系數是2的倍數.

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