用开平方法解方程4(x+1)²=k 用配方法解2x²+3x=1,3x²-2=4x,(x+3)(x-6)=-8写点过程谢谢
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用开平方法解方程4(x+1)²=k 用配方法解2x²+3x=1,3x²-2=4x,(x+3)(x-6)=-8写点过程谢谢
用开平方法解方程4(x+1)²=k 用配方法解2x²+3x=1,3x²-2=4x,(x+3)(x-6)=-8
写点过程谢谢
用开平方法解方程4(x+1)²=k 用配方法解2x²+3x=1,3x²-2=4x,(x+3)(x-6)=-8写点过程谢谢
答:
1)
4(x+1)²=k
2(x+1)=±√k
x+1=±(√k) /2
x=-1±(√k) /2
2)
2x²+3x=1
2(x²+3x/2+9/4)=1+9/2
2(x+3/2)²=11/2
(x+3/2)²=11/4
x+3/2=±√11/2
x=(-3±√11)/2
3)
3x²-2=4x
3x²-4x=2
3(x²-4x/3+4/9)=2+4/3
3(x-2/3)²=10/3
x-2/3=±√10/3
x=(2±√10)/3
4)
(x+3)(x-6)=-8
x²-3x-18=-8
x²-3x+9/4=10+9/4
(x-3/2)²=49/4
x-3/2=±7/2
x=(3±7)/2
x=5或者x=-2