mdsk.net
当前位置:首页 >> ABC的三次方公式 >>

ABC的三次方公式

原式=a^3 + b^3 + c^3 + 3a^2b + 3ab^2 + 3a^2c + 3b^2c + 3ac^2 + 3bc^2 + 6abc

(a+b+c)=a+b+c+3ab+3ac+3ab+3ac+3bc+3bc+6abc

(a+b+c)^3=a^3+b^3+c^3+3ab^2+3ac^2+3bc^2+3ba^2+3ca^2+3cb^2+6abc

完全立方公式:(a+b)^3=a^3+b^3+3ab^2+3a^2b(a-b)^3=a^3-b^3+3ab^2-3a^2b 立方和公式:a^3+b^3=(a+b)(a^2-ab+b^2) a^3-b^3=(a-b)(a^2+ab+b^2)

反复用两数和的立方公式: (a+b+c)^3 =(a+b)^3+3(a+b)^2c+3(a+b)c^2+c^3 =a^3+3a^2b+3ab^2+b^3+3(a^2+2ab+b^2)c+3ac^2+3bc^2+c^3 =a^3+b^3+c^3+3a^2b+3ab^2+3a^2c+3ac^2+3b^2c+3bc^2+6abc.

x^3+y^3=(x+y)(x^2-xy+y^2)x^3-y^3=(x-y)(x^2+xy+y^2)

(a b c)3=(a b c)2(a b c) =[(a b)2 c2 2(a b)c](a b c) =[a2 b2 2ab c2 2ac 2bc](a b c) =[a2 b2 c2 2(ab bc ac)](a b c) =a3 a2b a2c ab2 b3 b2c ac2 bc2 c3 2(a2b ab2 abc abc b2c bc2 a2c abc ac2) =a3 b3 c3 3(a2b a2c ab2 b2c ac2 bc2) 6abc =a3 b3 c3 3[a2(b c) b2(a c) c2(a b)] 6abc

a+b=(a+b)(a-ab+b)a-b=(a-b)(a+ab+b)a±3ab+3ab±b=(a±b)a+b+c-3abc=(a+b+c)(a+b+c-ab-ac-b

※ 说明:题目中" ^ "表次方数,如x的3次方写为x^3 . (D)1. 设f(x)=5x^4-6x^3+7x^2+8x-5 则degf(x)=(A)1 (B)2 (C)3 (D)4 (A)2. 若a≠0,b=0 则多项式 ax^3+bx^2+x+2 之次数为(A)3 (B)2 (C)1 (D)0 (B)3. 若f(x)=ax^3+bx^2+2x-3,其中a=0,b≠0,

^^a+b+c-3abc=(a+b+c)(a+b+c-ab-bc-ca) (a+b+c)^3 =(a+b)^3+3(a+b)^2c+3(a+b)c^2+c^3 =a^3+3a^2b+3ab^2+b^3+3a^2c+6abc+3b^2c+3ac^2+3bc^2+c^3

qhnw.net | alloyfurniture.com | tuchengsm.com | gmcy.net | zmqs.net | 网站首页 | 网站地图
All rights reserved Powered by www.mdsk.net
copyright ©right 2010-2021。
内容来自网络,如有侵犯请联系客服。zhit325@qq.com