初中数学必背公式大全-天气预报

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初中数学必背公式大全

更新时间： 2021-04-26 01:51:11

1、乘法与因式分解

a2-b2=(a+b)(a-b)

a3+b3=(a+b)(a2-ab+b2)

a3-b3=(a-b(a2+ab+b2)

2、三角不等式

|a+b|≤|a|+|b|

|a-b|≤|a|+|b|

|a|≤b-b≤a≤b

|a-b|≥|a|-|b|

-|a|≤a≤|a|

3、一元二次方程的解

-b+√(b2-4ac)/2a -b-√(b2-4ac)/2a

根与系数的关系

X1+X2=-b/aX1*X2=c/a

注：韦达定理

4、判别式

b2-4ac=0 注：方程有两个相等的实根

b2-4ac>0 注：方程有两个不等的实根

b2-4ac

关键词：初中数学公式大全

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