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InterviewSolution
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must betow many terms of thetaken so that their sum is 180e Arithmetic Progression 45, 39, 33,? Explain the double answer. |
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Answer» Given A.P is:-45,39,33....a₁=45;d=39-45=-6Given:-Sₙ=180n=?n/2[2a₁+(n-1)d]=180=>n/2[90+(n-1)×-6]=180=>n[90-6n+6]=360=>-6n²+96n-360=0=>6n²-96n+360=0=>n²-16n+60=0=>n²-10n-6n+60=0=>n(n-10)-6(n-10)=0=>(n-10)(n-6)=0=>n=10 or 6 |
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