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## Prove that $\frac1{a(1+b)}+\frac1{b(1+c)}+\frac1{c(1+a)}\ge\frac3{1+abc}$

I tried doing it with CS-Engel to get $$\frac{1}{a(1+b)}+\frac{1}{b(1+c)}+\frac{1}{c(1+a)} \geq \frac{9}{a+b+c+ a b+b c+a c}$$ I thought that maybe proof that $$\frac{1}{a+b+c+a b+b c+a c} \geq \frac{1}{3(1+a b c)}$$ or $$3+3 a b c \geq a+b+c+a b+b c+a c$$, but I don’t know how

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## Prove that $\frac1{a(1+b)}+\frac1{b(1+c)}+\frac1{c(1+a)}\ge\frac3{1+abc}$

I tried doing it with CS-Engel to get $$\frac{1}{a(1+b)}+\frac{1}{b(1+c)}+\frac{1}{c(1+a)} \geq \frac{9}{a+b+c+ a b+b c+a c}$$ I thought that maybe proof that $$\frac{1}{a+b+c+a b+b c+a c} \geq \frac{1}{3(1+a b c)}$$ or $$3+3 a b c \geq a+b+c+a b+b c+a c$$, but I don’t know how

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## Proof that 1/(a(1+b))+1/(b(1+c))+1/(c(1+a))>=3/(1+abc)

I tried doing it with CS-Engel to get $$\frac{1}{a(1+b)}+\frac{1}{b(1+c)}+\frac{1}{c(1+a)} \geq \frac{9}{a+b+c+ a b+b c+a c}$$ I thought that maybe proof that $$\frac{1}{a+b+c+a b+b c+a c} \geq \frac{1}{3(1+a b c)}$$ or $$3+3 a b c \geq a+b+c+a b+b c+a c$$, but I don’t know how