SOLUTION: Solve the system: y=2x+1 and x^2 + y^2 =25. Do I do this with graphing or substitution? Please provide solution thanks

Algebra ->  Systems-of-equations -> SOLUTION: Solve the system: y=2x+1 and x^2 + y^2 =25. Do I do this with graphing or substitution? Please provide solution thanks      Log On


   

Question 246121: Solve the system: y=2x+1 and x^2 + y^2 =25. Do I do this with graphing or substitution? Please provide solution
thanks
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Solve the system: y=2x+1 and x^2 + y^2 =25. Do I do this with graphing or substitution? Please provide solution
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Substitution:
x^2 + (2x+1)^2 = 25
x^2 + 4x^2 + 4x + 1 = 25
5x^2 +4x - 24 = 0
x = [-4+-sqrt(16 - 4*5*-24)]/10
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x = [-4 +- sqrt(496)]/10
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x = [-4 +- 4sqrt(31)]/10
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x = [-2+2sqrt(31)]/5 or x = [-2-2sqrt(31)]/5
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x = 1.8271 or x = -2.6271
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Find the y-value associated with each of these x-values.
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Cheers,
Stan H.