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Question Number 82667 by M±th+et£s last updated on 23/Feb/20
if a>0  b>0  a≤b    show that   a^2 ≤(((2ab)/(a+b)))^2 ≤ab≤(((a+b)/2))^2 ≤((a^2 +b^2 )/2)≤b^2
ifa>0b>0abshowthata2(2aba+b)2ab(a+b2)2a2+b22b2
Answered by TANMAY PANACEA last updated on 23/Feb/20
b^2 −((a^2 +b^2 )/2)  (((b+a)(b−a))/2)>0  so b^2 >((a^2 +b^2 )/2)  [equality sivn if a=b]  ((a^2 +b^2 )/2)−(((a+b)/2))^2   =((2a^2 +2b^2 −a^2 −b^2 −2ab)/4)→(((b−a)^2 )/2^2 )>0  so ((a^2 +b^2 )/2)>(((a+b)/2))^2   (((a+b)/2))^2 −ab  =(((a−b)^2 )/2^2 )   so (((a+b)/2))^2 >ab  ab−(((2ab)/(a+b)))^2   =ab×((a^2 +2ab+b^2 −4ab)/((a+b)^2 ))→ab×(((a−b)/(a+b)))^2   so ab>(((2ab)/(a+b)))^2   (((2ab)/(a+b)))^2 −a^2   =a^2 ×((4b^2 −a^2 −2ab−b^2 )/((a+b)^2 ))  (a^2 /((a+b)^2 ))×(3b^2 −3ab+ab−a^2 )  (a^2 /((a+b)^2 ))×{3b(b−a)+a(b−a)}  (a^2 /((a+b)^2 ))×(b−a)(3b+a)>0  since b>a
b2a2+b22(b+a)(ba)2>0sob2>a2+b22[equalitysivnifa=b]a2+b22(a+b2)2=2a2+2b2a2b22ab4(ba)222>0soa2+b22>(a+b2)2(a+b2)2ab=(ab)222so(a+b2)2>abab(2aba+b)2=ab×a2+2ab+b24ab(a+b)2ab×(aba+b)2soab>(2aba+b)2(2aba+b)2a2=a2×4b2a22abb2(a+b)2a2(a+b)2×(3b23ab+aba2)a2(a+b)2×{3b(ba)+a(ba)}a2(a+b)2×(ba)(3b+a)>0sinceb>a
Commented by M±th+et£s last updated on 23/Feb/20
god bless you sir
godblessyousir
Commented by TANMAY PANACEA last updated on 23/Feb/20
blessing shoser to all
blessingshosertoall

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