System of equations

Algebra Level 3

a 2 + 2 b = 7 \mathcal{a^{2} + 2b = 7}

b 2 + 4 c = 7 \mathcal{ b^{2} + 4c = -7}

c 2 + 6 a = 14 \mathcal{ c^{2} + 6a = -14}

Find the sum of the real roots

can you solve it in 60 seconds


The answer is -6.

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1 solution

Ronald Overwater
Nov 4, 2014

Add all three equations to get: a 2 + 6 a + b 2 + 2 b + c 2 + 4 c = 14 a^2+6a+b^2+2b+c^2+4c=-14

( a + 3 ) 2 + ( b + 1 ) 2 + ( c + 2 ) 2 = 0 (a+3)^2+(b+1)^2+(c+2)^2=0

And because all squares are non-negative, there is only one solution:

( a + 3 ) = 0 ; ( b + 1 ) = 0 ; ( c + 2 ) = 0 (a+3)=0; (b+1)=0; (c+2)=0

Or a = 3 ; b = 1 a=-3; b=-1 and c = 2 c=-2 as the only real solution.

a + b + c = 6 a+b+c=-6

YEPP I DID THE SAME!

Apurva Surve - 6 years, 6 months ago

exactly , really well done @Ronald Overwater

You have overcame the challenge

U Z - 6 years, 7 months ago

why didnt i think like that

prajwal kavad - 6 years, 4 months ago

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