Question

Câu 1 ; Ba số a;b ; c khác nhau và khác 0 thỏa mãn \(\dfrac{a}{b+c}=\dfrac{b}{b+c}=\dfrac{c}{a+b}\).

Giá trị P = \(\dfrac{a}{b}+\dfrac{b}{a}+\dfrac{a}{c}+\dfrac{c}{a}+\dfrac{b}{c}+\dfrac{c}{b}\)

Tính P =

Câu 2 : Tìm x , biết :

\(\dfrac{1+3y}{12}=\dfrac{1+5y}{5x}=\dfrac{1+7y}{2}\)

giúp mk nha

Answer 1

\(\dfrac{a}{b+c}=\dfrac{b}{b+c}=\dfrac{c}{a+b}=\dfrac{a+b+c}{2\left(a+b+c\right)}=\dfrac{1}{2}\)

\(\dfrac{a}{b+c}=\dfrac{1}{2}\Rightarrow\dfrac{b+c}{a}=2\)

tuong tu \(\dfrac{b+c}{b}=2,\dfrac{a+b}{c}=2.\)

P= (a/b+c/b)+(b/a+c/a)+(a/c+b/c)= \(\dfrac{a+c}{b}+\dfrac{b+c}{a}+\dfrac{a+b}{c}=2+2+2=6\)

Answer 2

câu 2: bài ra \(\Rightarrow\dfrac{1+5y}{5x}=\dfrac{1+3y}{12}=\dfrac{2+10y}{10x}=\dfrac{1+7y}{10x-12}\)

suy ra \(\dfrac{1+7y}{2}=\dfrac{1+7y}{10x-12}\)

\(\Rightarrow\) 2=10x-12

vay x=\(\dfrac{7}{5}\)