Inequality $frac{a^2}{b}+frac{b^2}{c}+frac{c^2}{a}+15sqrt[3]{abc}geq 6(a+b+c).$
Let $a,b$ and $c$ are positive numbers. Prove that
$$dfrac{a^2}{b}+dfrac{b^2}{c}+dfrac{c^2}{a}+15sqrt[3]{abc}geq 6(a+b+c).$$
I tried BW, SOS-Schur, but without any success.
I let $abc=1$. Then assuming $a=y/x,b=z/y,c=x/z$.
I got a six degree polynomial. But , I failed to complete the proof.
inequality buffalo-way
add a comment |
Let $a,b$ and $c$ are positive numbers. Prove that
$$dfrac{a^2}{b}+dfrac{b^2}{c}+dfrac{c^2}{a}+15sqrt[3]{abc}geq 6(a+b+c).$$
I tried BW, SOS-Schur, but without any success.
I let $abc=1$. Then assuming $a=y/x,b=z/y,c=x/z$.
I got a six degree polynomial. But , I failed to complete the proof.
inequality buffalo-way
I know that you are strong enough in inequalities.What is your trying? Show please. Otherwise, I can't show to you my solution.
– Michael Rozenberg
Nov 6 '18 at 5:37
I tried BW, SOS-Schur, but without any success.
– yao4015
Nov 6 '18 at 5:42
BW helps here, but I think there is something more nicer.
– Michael Rozenberg
Nov 6 '18 at 5:58
add a comment |
Let $a,b$ and $c$ are positive numbers. Prove that
$$dfrac{a^2}{b}+dfrac{b^2}{c}+dfrac{c^2}{a}+15sqrt[3]{abc}geq 6(a+b+c).$$
I tried BW, SOS-Schur, but without any success.
I let $abc=1$. Then assuming $a=y/x,b=z/y,c=x/z$.
I got a six degree polynomial. But , I failed to complete the proof.
inequality buffalo-way
Let $a,b$ and $c$ are positive numbers. Prove that
$$dfrac{a^2}{b}+dfrac{b^2}{c}+dfrac{c^2}{a}+15sqrt[3]{abc}geq 6(a+b+c).$$
I tried BW, SOS-Schur, but without any success.
I let $abc=1$. Then assuming $a=y/x,b=z/y,c=x/z$.
I got a six degree polynomial. But , I failed to complete the proof.
inequality buffalo-way
inequality buffalo-way
edited Nov 27 '18 at 12:20
Martin Sleziak
44.7k7115270
44.7k7115270
asked Nov 6 '18 at 5:34
yao4015
655
655
I know that you are strong enough in inequalities.What is your trying? Show please. Otherwise, I can't show to you my solution.
– Michael Rozenberg
Nov 6 '18 at 5:37
I tried BW, SOS-Schur, but without any success.
– yao4015
Nov 6 '18 at 5:42
BW helps here, but I think there is something more nicer.
– Michael Rozenberg
Nov 6 '18 at 5:58
add a comment |
I know that you are strong enough in inequalities.What is your trying? Show please. Otherwise, I can't show to you my solution.
– Michael Rozenberg
Nov 6 '18 at 5:37
I tried BW, SOS-Schur, but without any success.
– yao4015
Nov 6 '18 at 5:42
BW helps here, but I think there is something more nicer.
– Michael Rozenberg
Nov 6 '18 at 5:58
I know that you are strong enough in inequalities.What is your trying? Show please. Otherwise, I can't show to you my solution.
– Michael Rozenberg
Nov 6 '18 at 5:37
I know that you are strong enough in inequalities.What is your trying? Show please. Otherwise, I can't show to you my solution.
– Michael Rozenberg
Nov 6 '18 at 5:37
I tried BW, SOS-Schur, but without any success.
– yao4015
Nov 6 '18 at 5:42
I tried BW, SOS-Schur, but without any success.
– yao4015
Nov 6 '18 at 5:42
BW helps here, but I think there is something more nicer.
– Michael Rozenberg
Nov 6 '18 at 5:58
BW helps here, but I think there is something more nicer.
– Michael Rozenberg
Nov 6 '18 at 5:58
add a comment |
1 Answer
1
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oldest
votes
BW helps here!
We need to prove that
$$frac{a^6}{b^3}+frac{b^6}{c^3}+frac{c^6}{a^3}+15abcgeq6(a^3+b^3+c^3).$$
Now, let $a=min{a,b,c}$, $b=a+u$ and $c=a+v$.
Thus, we need to prove that:
$$3(u^2-uv+v^2)a^{10}+(13u^3-45u^2v+36uv^2+13v^3)a^9+$$
$$+3(17u^4-55u^3v+18u^2v^2+26uv^3+17v^4)a^8+$$
$$+6(15u^5-35u^4v-12u^2v^2+24u^2v^3+28uv^4+15v^5)a^7+$$
$$+6(13u^6-18u^5v-30u^4v^2+13u^3v^3+33u^2v^4+45uv^5+13v^6)a^6+$$
$$+6(6u^7-3u^6v-18u^5v^2-5u^4v^3+16u^3v^4+45u^2v^5+39uv^6+6v^7)a^5+$$
$$+3(3u^8-6u^6v^2-12u^5v^3+5u^4v^4+30u^3v^5+78u^2v^6+36uv^7+3u^8)a^4+$$
$$+(u^9-6u^6v^3+78u^3v^6+108u^2v^7+27uv^8+v^9)a^3+$$
$$+3(12u^2+9uv+v^2)uv^7a^2+3u^2v^8a(3u+v)+u^3v^9geq0,$$ which is true because
$$3(u^2-uv+v^2)geq3uv,$$
$$13u^3-45u^2v+36uv^2+13v^3geq3sqrt{u^3v^3},$$
$$3(17u^4-55u^3v+18u^2v^2+26uv^3+17v^4)geq-21u^2v^2,$$
$$6(15u^5-35u^4v-12u^2v^2+24u^2v^3+28uv^4+15v^5)geq-16sqrt{u^5v^5},$$
$$6(13u^6-18u^5v-30u^4v^2+13u^3v^3+33u^2v^4+45uv^5+13v^6)geq65u^3v^3,$$
$$6(6u^7-3u^6v-18u^5v^2-5u^4v^3+16u^3v^4+45u^2v^5+39uv^6+6v^7)geq144sqrt{u^7v^7},$$
$$3(3u^8-6u^6v^2-12u^5v^3+5u^4v^4+30u^3v^5+78u^2v^6+36uv^7+3u^8)geq127u^4v^4$$ and
$$u^9-6u^6v^3+78u^3v^6+108u^2v^7+27uv^8+v^9geq88sqrt{u^9v^9}.$$
Now, let $frac{a}{sqrt{uv}}=x$.
Thus, it's enough to prove that
$$3x^7+3x^6-21x^5-16x^4+65x^3+144x^2+127x+88geq0,$$ which is obvious.
Firstly, I let $abc=1$ . Then assuming $ a=y/x, b=z/y,c=x/z$ .I got a six degree polynomial. But , I failed to complete the proof. I want to see more beautiful proofs.
– yao4015
Nov 6 '18 at 8:33
add a comment |
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BW helps here!
We need to prove that
$$frac{a^6}{b^3}+frac{b^6}{c^3}+frac{c^6}{a^3}+15abcgeq6(a^3+b^3+c^3).$$
Now, let $a=min{a,b,c}$, $b=a+u$ and $c=a+v$.
Thus, we need to prove that:
$$3(u^2-uv+v^2)a^{10}+(13u^3-45u^2v+36uv^2+13v^3)a^9+$$
$$+3(17u^4-55u^3v+18u^2v^2+26uv^3+17v^4)a^8+$$
$$+6(15u^5-35u^4v-12u^2v^2+24u^2v^3+28uv^4+15v^5)a^7+$$
$$+6(13u^6-18u^5v-30u^4v^2+13u^3v^3+33u^2v^4+45uv^5+13v^6)a^6+$$
$$+6(6u^7-3u^6v-18u^5v^2-5u^4v^3+16u^3v^4+45u^2v^5+39uv^6+6v^7)a^5+$$
$$+3(3u^8-6u^6v^2-12u^5v^3+5u^4v^4+30u^3v^5+78u^2v^6+36uv^7+3u^8)a^4+$$
$$+(u^9-6u^6v^3+78u^3v^6+108u^2v^7+27uv^8+v^9)a^3+$$
$$+3(12u^2+9uv+v^2)uv^7a^2+3u^2v^8a(3u+v)+u^3v^9geq0,$$ which is true because
$$3(u^2-uv+v^2)geq3uv,$$
$$13u^3-45u^2v+36uv^2+13v^3geq3sqrt{u^3v^3},$$
$$3(17u^4-55u^3v+18u^2v^2+26uv^3+17v^4)geq-21u^2v^2,$$
$$6(15u^5-35u^4v-12u^2v^2+24u^2v^3+28uv^4+15v^5)geq-16sqrt{u^5v^5},$$
$$6(13u^6-18u^5v-30u^4v^2+13u^3v^3+33u^2v^4+45uv^5+13v^6)geq65u^3v^3,$$
$$6(6u^7-3u^6v-18u^5v^2-5u^4v^3+16u^3v^4+45u^2v^5+39uv^6+6v^7)geq144sqrt{u^7v^7},$$
$$3(3u^8-6u^6v^2-12u^5v^3+5u^4v^4+30u^3v^5+78u^2v^6+36uv^7+3u^8)geq127u^4v^4$$ and
$$u^9-6u^6v^3+78u^3v^6+108u^2v^7+27uv^8+v^9geq88sqrt{u^9v^9}.$$
Now, let $frac{a}{sqrt{uv}}=x$.
Thus, it's enough to prove that
$$3x^7+3x^6-21x^5-16x^4+65x^3+144x^2+127x+88geq0,$$ which is obvious.
Firstly, I let $abc=1$ . Then assuming $ a=y/x, b=z/y,c=x/z$ .I got a six degree polynomial. But , I failed to complete the proof. I want to see more beautiful proofs.
– yao4015
Nov 6 '18 at 8:33
add a comment |
BW helps here!
We need to prove that
$$frac{a^6}{b^3}+frac{b^6}{c^3}+frac{c^6}{a^3}+15abcgeq6(a^3+b^3+c^3).$$
Now, let $a=min{a,b,c}$, $b=a+u$ and $c=a+v$.
Thus, we need to prove that:
$$3(u^2-uv+v^2)a^{10}+(13u^3-45u^2v+36uv^2+13v^3)a^9+$$
$$+3(17u^4-55u^3v+18u^2v^2+26uv^3+17v^4)a^8+$$
$$+6(15u^5-35u^4v-12u^2v^2+24u^2v^3+28uv^4+15v^5)a^7+$$
$$+6(13u^6-18u^5v-30u^4v^2+13u^3v^3+33u^2v^4+45uv^5+13v^6)a^6+$$
$$+6(6u^7-3u^6v-18u^5v^2-5u^4v^3+16u^3v^4+45u^2v^5+39uv^6+6v^7)a^5+$$
$$+3(3u^8-6u^6v^2-12u^5v^3+5u^4v^4+30u^3v^5+78u^2v^6+36uv^7+3u^8)a^4+$$
$$+(u^9-6u^6v^3+78u^3v^6+108u^2v^7+27uv^8+v^9)a^3+$$
$$+3(12u^2+9uv+v^2)uv^7a^2+3u^2v^8a(3u+v)+u^3v^9geq0,$$ which is true because
$$3(u^2-uv+v^2)geq3uv,$$
$$13u^3-45u^2v+36uv^2+13v^3geq3sqrt{u^3v^3},$$
$$3(17u^4-55u^3v+18u^2v^2+26uv^3+17v^4)geq-21u^2v^2,$$
$$6(15u^5-35u^4v-12u^2v^2+24u^2v^3+28uv^4+15v^5)geq-16sqrt{u^5v^5},$$
$$6(13u^6-18u^5v-30u^4v^2+13u^3v^3+33u^2v^4+45uv^5+13v^6)geq65u^3v^3,$$
$$6(6u^7-3u^6v-18u^5v^2-5u^4v^3+16u^3v^4+45u^2v^5+39uv^6+6v^7)geq144sqrt{u^7v^7},$$
$$3(3u^8-6u^6v^2-12u^5v^3+5u^4v^4+30u^3v^5+78u^2v^6+36uv^7+3u^8)geq127u^4v^4$$ and
$$u^9-6u^6v^3+78u^3v^6+108u^2v^7+27uv^8+v^9geq88sqrt{u^9v^9}.$$
Now, let $frac{a}{sqrt{uv}}=x$.
Thus, it's enough to prove that
$$3x^7+3x^6-21x^5-16x^4+65x^3+144x^2+127x+88geq0,$$ which is obvious.
Firstly, I let $abc=1$ . Then assuming $ a=y/x, b=z/y,c=x/z$ .I got a six degree polynomial. But , I failed to complete the proof. I want to see more beautiful proofs.
– yao4015
Nov 6 '18 at 8:33
add a comment |
BW helps here!
We need to prove that
$$frac{a^6}{b^3}+frac{b^6}{c^3}+frac{c^6}{a^3}+15abcgeq6(a^3+b^3+c^3).$$
Now, let $a=min{a,b,c}$, $b=a+u$ and $c=a+v$.
Thus, we need to prove that:
$$3(u^2-uv+v^2)a^{10}+(13u^3-45u^2v+36uv^2+13v^3)a^9+$$
$$+3(17u^4-55u^3v+18u^2v^2+26uv^3+17v^4)a^8+$$
$$+6(15u^5-35u^4v-12u^2v^2+24u^2v^3+28uv^4+15v^5)a^7+$$
$$+6(13u^6-18u^5v-30u^4v^2+13u^3v^3+33u^2v^4+45uv^5+13v^6)a^6+$$
$$+6(6u^7-3u^6v-18u^5v^2-5u^4v^3+16u^3v^4+45u^2v^5+39uv^6+6v^7)a^5+$$
$$+3(3u^8-6u^6v^2-12u^5v^3+5u^4v^4+30u^3v^5+78u^2v^6+36uv^7+3u^8)a^4+$$
$$+(u^9-6u^6v^3+78u^3v^6+108u^2v^7+27uv^8+v^9)a^3+$$
$$+3(12u^2+9uv+v^2)uv^7a^2+3u^2v^8a(3u+v)+u^3v^9geq0,$$ which is true because
$$3(u^2-uv+v^2)geq3uv,$$
$$13u^3-45u^2v+36uv^2+13v^3geq3sqrt{u^3v^3},$$
$$3(17u^4-55u^3v+18u^2v^2+26uv^3+17v^4)geq-21u^2v^2,$$
$$6(15u^5-35u^4v-12u^2v^2+24u^2v^3+28uv^4+15v^5)geq-16sqrt{u^5v^5},$$
$$6(13u^6-18u^5v-30u^4v^2+13u^3v^3+33u^2v^4+45uv^5+13v^6)geq65u^3v^3,$$
$$6(6u^7-3u^6v-18u^5v^2-5u^4v^3+16u^3v^4+45u^2v^5+39uv^6+6v^7)geq144sqrt{u^7v^7},$$
$$3(3u^8-6u^6v^2-12u^5v^3+5u^4v^4+30u^3v^5+78u^2v^6+36uv^7+3u^8)geq127u^4v^4$$ and
$$u^9-6u^6v^3+78u^3v^6+108u^2v^7+27uv^8+v^9geq88sqrt{u^9v^9}.$$
Now, let $frac{a}{sqrt{uv}}=x$.
Thus, it's enough to prove that
$$3x^7+3x^6-21x^5-16x^4+65x^3+144x^2+127x+88geq0,$$ which is obvious.
BW helps here!
We need to prove that
$$frac{a^6}{b^3}+frac{b^6}{c^3}+frac{c^6}{a^3}+15abcgeq6(a^3+b^3+c^3).$$
Now, let $a=min{a,b,c}$, $b=a+u$ and $c=a+v$.
Thus, we need to prove that:
$$3(u^2-uv+v^2)a^{10}+(13u^3-45u^2v+36uv^2+13v^3)a^9+$$
$$+3(17u^4-55u^3v+18u^2v^2+26uv^3+17v^4)a^8+$$
$$+6(15u^5-35u^4v-12u^2v^2+24u^2v^3+28uv^4+15v^5)a^7+$$
$$+6(13u^6-18u^5v-30u^4v^2+13u^3v^3+33u^2v^4+45uv^5+13v^6)a^6+$$
$$+6(6u^7-3u^6v-18u^5v^2-5u^4v^3+16u^3v^4+45u^2v^5+39uv^6+6v^7)a^5+$$
$$+3(3u^8-6u^6v^2-12u^5v^3+5u^4v^4+30u^3v^5+78u^2v^6+36uv^7+3u^8)a^4+$$
$$+(u^9-6u^6v^3+78u^3v^6+108u^2v^7+27uv^8+v^9)a^3+$$
$$+3(12u^2+9uv+v^2)uv^7a^2+3u^2v^8a(3u+v)+u^3v^9geq0,$$ which is true because
$$3(u^2-uv+v^2)geq3uv,$$
$$13u^3-45u^2v+36uv^2+13v^3geq3sqrt{u^3v^3},$$
$$3(17u^4-55u^3v+18u^2v^2+26uv^3+17v^4)geq-21u^2v^2,$$
$$6(15u^5-35u^4v-12u^2v^2+24u^2v^3+28uv^4+15v^5)geq-16sqrt{u^5v^5},$$
$$6(13u^6-18u^5v-30u^4v^2+13u^3v^3+33u^2v^4+45uv^5+13v^6)geq65u^3v^3,$$
$$6(6u^7-3u^6v-18u^5v^2-5u^4v^3+16u^3v^4+45u^2v^5+39uv^6+6v^7)geq144sqrt{u^7v^7},$$
$$3(3u^8-6u^6v^2-12u^5v^3+5u^4v^4+30u^3v^5+78u^2v^6+36uv^7+3u^8)geq127u^4v^4$$ and
$$u^9-6u^6v^3+78u^3v^6+108u^2v^7+27uv^8+v^9geq88sqrt{u^9v^9}.$$
Now, let $frac{a}{sqrt{uv}}=x$.
Thus, it's enough to prove that
$$3x^7+3x^6-21x^5-16x^4+65x^3+144x^2+127x+88geq0,$$ which is obvious.
edited Nov 6 '18 at 6:29
answered Nov 6 '18 at 6:12
Michael Rozenberg
96.2k1588186
96.2k1588186
Firstly, I let $abc=1$ . Then assuming $ a=y/x, b=z/y,c=x/z$ .I got a six degree polynomial. But , I failed to complete the proof. I want to see more beautiful proofs.
– yao4015
Nov 6 '18 at 8:33
add a comment |
Firstly, I let $abc=1$ . Then assuming $ a=y/x, b=z/y,c=x/z$ .I got a six degree polynomial. But , I failed to complete the proof. I want to see more beautiful proofs.
– yao4015
Nov 6 '18 at 8:33
Firstly, I let $abc=1$ . Then assuming $ a=y/x, b=z/y,c=x/z$ .I got a six degree polynomial. But , I failed to complete the proof. I want to see more beautiful proofs.
– yao4015
Nov 6 '18 at 8:33
Firstly, I let $abc=1$ . Then assuming $ a=y/x, b=z/y,c=x/z$ .I got a six degree polynomial. But , I failed to complete the proof. I want to see more beautiful proofs.
– yao4015
Nov 6 '18 at 8:33
add a comment |
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I know that you are strong enough in inequalities.What is your trying? Show please. Otherwise, I can't show to you my solution.
– Michael Rozenberg
Nov 6 '18 at 5:37
I tried BW, SOS-Schur, but without any success.
– yao4015
Nov 6 '18 at 5:42
BW helps here, but I think there is something more nicer.
– Michael Rozenberg
Nov 6 '18 at 5:58