Áp dụng bđt AM - GM:

\(T=\dfrac{a+b+c}{\sqrt[3]{abc}}+\dfrac{\sqrt[3]{abc}}{a+b+c}=\left(\dfrac{1}{9}\dfrac{a+b+c}{\sqrt[3]{abc}}+\dfrac{\sqrt[3]{abc}}{a+b+c}\right)+\dfrac{8}{9}\dfrac{a+b+c}{\sqrt[3]{abc}}\ge2\sqrt{\dfrac{1}{9}}+\dfrac{8}{9}.3=\dfrac{2}{3}+\dfrac{8}{3}=\dfrac{10}{3}\).

Đẳng thức xảy ra khi a = b = c.

Vậy Min T = \(\dfrac{10}{3}\) khi a = b = c.

Ta có:\(m=\dfrac{b+c}{a}+\dfrac{c+a}{b}+\dfrac{a+b}{c}\)

\(m=\left(\dfrac{b+c}{a}+1\right)+\left(\dfrac{c+a}{b}+1\right)+\left(\dfrac{a+b}{c}+1\right)-3\)

\(m=\dfrac{a+b+c}{a}+\dfrac{a+b+c}{b}+\dfrac{a+b+c}{c}-3\)

\(m=\left(a+b+c\right)\left(\dfrac{1}{a}+\dfrac{1}{b}+\dfrac{1}{c}\right)-3\)

\(m=0-3=-3\)

a: \(P=\dfrac{a+3}{a}\cdot\dfrac{a^2-9-6a+18}{\left(a-3\right)\left(a+3\right)}\)

\(=\dfrac{\left(a-3\right)^2}{a\left(a-3\right)}=\dfrac{a-3}{a}\)

b: Để P=-2 thì -2a=a-3

=>-3a=-3

=>a=1

c: Để P nguyên thì a-3 chia hết cho a

=>-3 chia hết cho a

mà a<>0; a<>3; a<>-3

nên \(a\in\left\{1;-1\right\}\)

b \(P=\dfrac{\sqrt{x}+\sqrt{x}+2}{x-4}\cdot\dfrac{\sqrt{x}-2}{2}=\dfrac{\sqrt{x}+1}{\sqrt{x}+2}\)

a: Khi x=64 thì \(P=\dfrac{8+1}{8+2}=\dfrac{9}{10}\)