1/ M= $\frac{b-c}{a^{2}-ac-ab+bc }$ + $\frac{c-a}{b^{2}-ab-cb+ca }$ + $\frac{a-b}{c^{2}-cb-ac+ab}$
N= $\frac{1}{a-b}$ + $\frac{1}{b-c}$ + $\frac{1}{c-a}$
Chứng minh M=2N
2/ Cho $\frac{x}{a}$ + $\frac{y}{b}$ + $\frac{z}{c}$ = 0
Và $\frac{a}{x}$ + $\frac{b}{y}$ + $\frac{c}{z}$ = 2
Cmr $\frac{a}{bcx^{2}}$ + $\frac{b}{acy^{2}}$ + $\frac{c}{abz^{2}}$ = $\frac{4}{abc}$
1/ M= $\frac{b-c}{a^{2}-ac-ab+bc }$ + $\frac{c-a}{b^{2}-ab-cb+ca }$ + $\frac{a-b}{c^{2}-cb-ac+ab}$ N= $\frac{1}{a-b}$ + $\frac{1}{b-c}$ + $\frac{1}{c
By Lydia
Em tham khảo:
M=$\frac{b-c}{a^2-ac-ab+bc}+$ $\frac{c-a}{b^2-ab-cb+ca}+$ $\frac{a-b}{c-cb-ac+ab}$
M=$\frac{b-c}{(a-b)(a-c)}+$ $\frac{c-a}{(b-c)(b-a)}+$ $\frac{a-b}{(c-a)(c-b)}$
M=$\frac{b-c}{(a-b)(a-c)}-$ $\frac{c-a}{(b-c)(a-b)}+$ $\frac{a-b}{(a-c)(b-c)}$
M=$\frac{(b-c)^2-(c-a)(a-c)+(a-b)^2}{(a-b)(a-c)(b-c)}$
M=$\frac{2b^2-2ba+2a^2-2ac}{(a-b)(b-c)(a-c)}$
N=$\frac{1}{a-b}$ +$\frac{1}{b-c}+$$\frac{1}{c-a}$
N=