The sum of two numbers is 9 and the sum of their squares is 261

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The sum of two numbers is 9 and the sum of their squares is 261. Find the numbers. I'm not sure how to set this out algebraically. If you could help me to set it out as a quadratic equation, I should be able to get the answer from there. Thank you for your time LET THE NUMBERS BE X AND Y X+Y=9......................................I X^2+Y^2=261 USE THE FORMULA (X+Y)^2+(X-Y)^2=2(X^2+Y^2) 9^2+(X-Y)^2=2*261=522 (X-Y)^2=522-81=441 X-Y=+21..................II...OR....-21..............III EQN.I+EQN.II X+Y+X-Y=9+21=30 2X=30 X=15 Y=9-X=9-15=-6 OR X-Y=-21................................III EQN.III+EQN.I 2X=-12 X=-6 Y=9-X=9+6=15

HENCE THE 2 NUMBERS ARE 15 AND -6