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Question Number 49637 by Pk1167156@gmail.com last updated on 08/Dec/18

Answered by tanmay.chaudhury50@gmail.com last updated on 09/Dec/18

α+β=((−b)/a)   αβ=(c/a)  ((α+β)/(αβ))=((−b)/c)    α+β=((−b)/a)   α^2 +β^2 =(b^2 /a^2 )−((2c)/a)=((b^2 −2ac)/a^2 )  given  2b=a+c [since a,b and c are inA.P]  (((−b)/a))^2 =((−b)/c)×((b^2 −2ac)/a^2 )  ((a^2 +c^2 +2ac)/(4a^2 ))=((−a−c)/(2c))×((((a^2 +c^2 +2ac)/4)−2ac)/a^2 )  ((a^2 +c^2 +2ac)/4)=((−a−c)/(2c))×((a^2 +c^2 −2ac)/4)  c^2 ((a^2 /c^2 )+1+2(a/c))=((−1)/2)((a/c)+1)×(c^2 /4)((a^2 /c^2 )+1−((2a)/c))  (a/c)=k  k^2 +1+2k=((−1)/8)(k+1)(k^2 +1−2k)  8k^2 +8+16k=−1(k^3 +k−2k^2 +k^2 +1−2k)  8k^2 +8+16k=−k^3 +k^2 +k−1  k^3 +7k^2 +15k+9=0  k^3 +k^2 +6k^2 +6k+9k+9=0  k^2 (k+1)+6k(k+1)+9(k+1)=0  (k+1)(k^2 +6k+9)=0  (k+1)(k+3)(k+3)=0  so k=−1   or k=−3  (a/c)=−1   or (a/c)=−3

α+β=baαβ=caα+βαβ=bcα+β=baα2+β2=b2a22ca=b22aca2given2b=a+c[sincea,bandcareinA.P](ba)2=bc×b22aca2a2+c2+2ac4a2=ac2c×a2+c2+2ac42aca2a2+c2+2ac4=ac2c×a2+c22ac4c2(a2c2+1+2ac)=12(ac+1)×c24(a2c2+12ac)ac=kk2+1+2k=18(k+1)(k2+12k)8k2+8+16k=1(k3+k2k2+k2+12k)8k2+8+16k=k3+k2+k1k3+7k2+15k+9=0k3+k2+6k2+6k+9k+9=0k2(k+1)+6k(k+1)+9(k+1)=0(k+1)(k2+6k+9)=0(k+1)(k+3)(k+3)=0sok=1ork=3ac=1orac=3

Commented by Pk1167156@gmail.com last updated on 10/Dec/18

Thank you very much sir.

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