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Question Number 217952 by dscm last updated on 23/Mar/25

If x∈Z ∧y non-negative integer  such that  x^2 +10x+23=2^y   find out x,y

IfxZynonnegativeintegersuchthatx2+10x+23=2yfindoutx,y

Answered by Frix last updated on 23/Mar/25

x=−5±(√(2^y +2))  ⇒ (√(2^y +2))∈N ⇒ y=1 ⇒ x=−7∨x=−3

x=5±2y+22y+2Ny=1x=7x=3

Commented by dscm last updated on 23/Mar/25

Thanks sir, but what is the guarantee  that y=1 is only value for 2^y +2  to be perfect square.

Thankssir,butwhatistheguaranteethaty=1isonlyvaluefor2y+2tobeperfectsquare.

Answered by Ghisom last updated on 23/Mar/25

x=t−5  t^2 −2=2^y   ⇒ t=2n  4n^2 −2=2^y   2n^2 =2^(y−1) +1  ⇒ 2∣(2^(y−1) +1) ⇒ y=1 ⇒ n=±1 ⇒ t=±2 ⇒  x=±2−5  x=−7∨x=−3

x=t5t22=2yt=2n4n22=2y2n2=2y1+12(2y1+1)y=1n=±1t=±2x=±25x=7x=3

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