Condition on Coefficients For Coupled Quadratics To Have Solutions

Suppose the coefficients of two quadratic equations  
\[x^2+b_1x+c_1=0, \: x^2+b_2x+c_2=0\]
  have the relationship  
Then at least one of the equations have solutions. Proof Suppose neither equation has solutions. Then  
\[b_1^2-4c_1 , \: b_2^2-4c_2 \lt0\]
\[b_1^2-4c_1+b_2^2-4c_2 =(b_1^2+b_2^2)-4(c_1+c_2) \lt 0\]
Use the condition (1) above to give  
\[(b_1^2+b_2^2)-2b_1b_2=(b_1-b_2)^2 \lt 0\]
This is impossible since a square number is at least zero, so at least one equation has solutions.

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