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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 7: Chứng minh: Nếu a(y+z)=b(z+x)=c(x+y) trong đó a$\neq$ b$\neq$ c$\neq$ 0 thì ta có $\frac{y-z}{a(b-c)}$ =$\frac{z-x}{b(c-a)}$ =$\fra

Toán Lớp 7: Chứng minh:
Nếu a(y+z)=b(z+x)=c(x+y) trong đó a$\neq$ b$\neq$ c$\neq$ 0 thì ta có $\frac{y-z}{a(b-c)}$ =$\frac{z-x}{b(c-a)}$ =$\frac{x-y}{c(a-b)}$

Comments ( 1 )

  1. Lời giải và giải thích chi tiết:
    Ta có:
    $a(y+z)=b(z+x)=c(x+y)$
    $\to \dfrac{a(y+z)}{abc}=\dfrac{b(z+x)}{abc}=\dfrac{c(x+y)}{abc}$
    $\to \dfrac{y+z}{bc}=\dfrac{z+x}{ac}=\dfrac{x+y}{ab}=\dfrac{(y+z)-(z+x)}{bc-ac}=\dfrac{(z+x)-(x+y)}{ac-ab}=\dfrac{(x+y)-(y+z)}{ab-bc}$
    $\to \dfrac{(y+z)-(z+x)}{bc-ac}=\dfrac{(z+x)-(x+y)}{ac-ab}=\dfrac{(x+y)-(y+z)}{ab-bc}$
    $\to \dfrac{y-x}{c(b-a)}=\dfrac{z-y}{a(c-b)}=\dfrac{x-z}{b(a-c)}$
    $\to \dfrac{x-y}{c(a-b)}=\dfrac{y-z}{a(b-c)}=\dfrac{z-x}{b(c-a)}$
    $\to đpcm$

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222-9+11+12:2*14+14 = ? ( )