初三数学解答题、一元二次方程、速答。

2024-12-02 10:01:32
推荐回答(6个)
回答1:

1. 一元二次方程 x ² + ax + b = 0 的两个根是 0 和 -2
则: x ² + ax + b = x(x+2)=x²+2x=0
所以: a=2 b=0

2. 【(-3)^0 】- 【根号27】+ 【绝对值(1- 根号2 )】+ 【(根号3+根号2)分之1 】
=1-3*根号3+根号2-1+根号3-根号2
=-2*根号3

回答2:

(1)
x ² + ax + b = 0 的两个根是 0 和 -2 ,
由韦达定理得:
0-2=-a
0*(-2)=b
则:a=2;b=0

(2)
【(-3)^0 】- 【根号27】+ 【绝对值(1- 根号2 )】+ 【(根号3+根号2)分之1 】
=1-3√3+√2-1+√3-√2
=-2√3

回答3:

x ² + ax + b = 0
0-2=-a , a=2 , 0*(-2)=b , b=0
【(-3)^0 】- 【根号27】+ 【绝对值(1- 根号2 )】+ 【(根号3+根号2)分之1 】
=1-3√3+|1-√2|+1/(√3+√2)
=1-3√3+√2-1+√3-√2
=-2√3

回答4:

把x=0和x=-2带入得
b=0,4-2a+b=0
a=2

(-3)^0-根号27+|1-根号2|+1/(根号3+根号2)
=1-3根号3-1+根号2+(根号3-根号2)
=-2根号3

回答5:

将两个根代入原方程,得到二元一次方程组,可以求出a、b 的值
第二问,结果是-2根号3,【(-3)^0 】=1,【绝对值(1- 根号2 )】=根号2 -1
【(根号3+根号2)分之1 】=根号3-根号2,

回答6:

在方程ax ² + bx + c = 0中
X1*X2=4ac
X1+X2= -b/(2a)

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