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2x"-5x+2=0配方法

2x²+5x-4=0(用配方法) 匿名 | 浏览188 次 |举报 我有更好的答案2条回答 2x^2+5x-4=0 x^2+(5/2)x=2 x^2+(5/2)x+25...

2x^2-5x+2=0 x^2-5/2x+1=0 x^2-5/2x+(5/4)^2 -(5/4)^2 +1=0 (x-5/4)^2 =9/16 x-5/4 =3/4或x-5/2 =-3/4 x=2或x =1/2

用配方法应该这样做 2x*2-5x+2=0 x*2-2.5x+1=0 x*2-2.5+25\16=25\16-1 (x-5\4)*2=9\16 所以x-5\4=3\4或x-5\4=-3\4 x=2或x=1\2 望采纳,谢谢

2x²-5x-1=0 解:x²-5/2x-1/2=0(先将x²的系数变为1) x²-5/2x+(5/2÷2)²-1/2-(5/2÷2)²=0(通过x²和x的系数来决定平方和或平方差的常数项) x²-5/2x+25/16-33/16=0 x²-5/2x+25/4=33/16(两边同...

2x^2+5x+2=0其实这道题用配方法解麻烦,正确的解法应该刘因式分解不过既然你要配方法,就只好配方了2[x^2+(5/2)x]+2=02(x+5/4)^2+2-25/8=02(x+5/4)^2=9/8(x+5/4)^2=9/16x+5/4=3/4或x+5/4=-3/4x1=-1/2,x2=-2

(2x+1)(x+2)

2x^2-5x+3=0 2(x²-5x/2)+3=0 2(x-5/4)²+3-25/8=0 2(x-5/4)²=1/8 (x-5/4)²=1/16 x-5/4=±1/4 x=1或x=3/2 十字相乘法 2x^2-5x+3=0 (2x-3)(x-1)=0 x=1或x=3/2

2x^2-5x+1=0 2(x^2-5x/2+25/16)-25/8+1=0 2(x-5/4)^2=17/8 (x-5/4)^2=√17/16 x-5/4=±√17/4 x=±√17/4+5/4

2x²-5x-3=0 2(x²-5/2x)=3 2(x²-5/2x+25/16)=3+25/8 2(x-5/4)²=49/8 (x-5/4)²=49/16=(7/4)² x-5/4=±7/4 x=3或x=-1/2

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