Question

Tìm các số a,b,c biết
a/2 = b/3 = c/6 và a + b - c = 7

Answer 1

\(\dfrac{a}{2}=\dfrac{b}{3}=\dfrac{c}{6}=\dfrac{a+b-c}{2+3-6}=\dfrac{7}{-1}=-7\) 

\(\dfrac{a}{2}=-7\Rightarrow a=-14\)

\(\dfrac{b}{3}=-7\Rightarrow b=-21\)

 \(\dfrac{c}{6}=-7\Rightarrow c=-42\)

Vậy a=-14, b=-21, c=-42

Answer 2

Áp dụng tính chất dãy tỉ sổ bằng nhau, ta có:
\(\dfrac{a}{2}=\dfrac{b}{3}=\dfrac{c}{6}=\dfrac{a+b-c}{2+3-6}=\dfrac{7}{-1}=-7\)
\(\Rightarrow\left\{{}\begin{matrix}\dfrac{a}{2}=-7\\\dfrac{b}{3}=-7\\\dfrac{c}{6}=-7\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}a=\left(-7\right).2\\b=\left(-7\right).3\\c=\left(-7\right).6\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}a=-14\\b=-21\\c=-42\end{matrix}\right.\)
Vậy ....