Question

Answer 1

2:

1: \(\Leftrightarrow\dfrac{10a+b}{10b+c}=\dfrac{b}{c}\)

=>10ac+bc=10b^2+bc

=>ac=b^2

=>a/b=b/c=k

=>a=bk; b=ck

=>a=ck^2;b=ck

\(\dfrac{a^2+b^2}{b^2+c^2}=\dfrac{c^2k^4+c^2k^2}{c^2k^2+c^2}=k^2\)

a/c=ck^2/c=k^2

=>\(\dfrac{a^2+b^2}{b^2+c^2}=\dfrac{a}{c}\)

 

1:

1: 

a: |x+1/3|-2=-1

=>|x+1/3|=1

=>x+1/3=1 hoặc x+1/3=-1

=>x=-4/3(nhận) hoặc x=2/3(nhận)

Khi x=-4/3thì \(A=\dfrac{6\cdot\dfrac{-4}{3}-8}{2\cdot\dfrac{-4}{3}-3}=\dfrac{48}{17}\)

Khi x=2/3 thì A=12/5

b: \(A=\dfrac{6x-9+1}{2x-3}=3+\dfrac{1}{2x-3}\)

Để A lớn nhất thì 2x-3=1

=>2x=4

=>x=2

=>A=3+1=4