PUMPA - SMART LEARNING

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Consider the equation \(ax^2 + bx + c = 0\), where \(a \ne 0\).
 
The roots of the quadratic equation are −b+b2−4ac2a and −b−b2−4ac2a.
 
If \(\alpha\) and \(\beta\) are the roots of a quadratic equation \(ax^2 + bx + c = 0\), then:
 
\(\alpha =\) −b+b2−4ac2a and \(\beta =\) −b−b2−4ac2a
 
Sum of the roots \(=\) \(\alpha + \beta\)
 
\(=\) −b+b2−4ac2a \(+\) −b−b2−4ac2a
 
\(=\) −b+b2−4ac−b−b2−4ac2a
 
\(=\) −2b2a=−ba
Sum of the roots \(=\) \(\alpha + \beta\) \(=\) −ba
Product of the roots \(=\) \(\alpha \beta\)
 
\(=\) −b+b2−4ac2a \(\times\) −b−b2−4ac2a
 
\(=\) −b−b+−b−b2−4ac+b2−4ac−b+b2−4ac−b2−4ac2a×2a
 
\(=\) b2+bb2−4ac−bb2−4ac−b2−4ac4a2
 
\(=\) b2−b2+4ac4a2
 
\(=\) 4ac4a2=ca
Product of the roots \(=\) \(\alpha \beta\) \(=\) ca
Since \((x - \alpha)\) and \((x - \beta)\) are factors of \(ax^2 + bx + c = 0\):
 
\((x - \alpha) (x - \beta) = 0\)
 
\(\Rightarrow x^2 - \alpha x - \beta x + \alpha \beta = 0\)
 
\(\Rightarrow x^2 - (\alpha + \beta) x + \alpha \beta = 0\)
 
\(\Rightarrow x^2 - (\text{sum of roots}) x + \text{product of roots} = 0\)
If \(\alpha\) and \(\beta\) are the roots of a quadratic equation, then the general formula to construct the quadratic equation is \(x^2 - (\alpha + \beta) x + \alpha \beta = 0\).
 
That is, \( x^2 - (\text{sum of roots}) x + \text{product of roots} = 0\).