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A Quadratic simple Doubt From a Brilliant website BLOG

Sir, In the Picture .. Is the QUESTION ....

  • The roots of x^{2}+4x+5 two Complex number in the form of a±bi. What is the sum of a and b?

Or

  • The roots of x^{2}+4x+5 is two Complex numbers in the form of a±bi. What is the sum of a and b?

In the Question ... x = -2±i

then \(x_{1}\) = -2 + i .................or............... \(x_{2}\) = -2 - i

adding both the roots give

\(x_{1}\) + \(x _{2}\) = - 2 + i - 2 - i = - 4

then the answer to this Question is -4 ., but it is said that the answer is 3

Thank you

Note by Vamsi Krishna Appili
4 years, 6 months ago

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2 votes

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Thanks for highlighting the mistakes. I've made some edits, and changed the question.

You are correct in saying that \(x_1 , x_2 = -2 + i, -2 - i \). I forgot about the negative sign in front of \(a\). Note that this gives \(a= 2 \) and \(b=1 \) (or possibly -1).

Calvin Lin Staff - 4 years, 6 months ago

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As a native English speaker, I believe the question should be properly worded as, "The roots of x^{2}+4x+5 ARE two Complex numbers in the form of a±bi. What is the sum of a and b?"

Taylor Lau - 4 years, 6 months ago

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yes

thanks

Vamsi Krishna Appili - 4 years, 6 months ago

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