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Let a and b be the roots of 2x^2+7x+11=0. Find ab+a+b

 Feb 17, 2021
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We can use Vieta's Formulas. Because 2x^2 + 7x + 11 = 0, we have \(a=2, b=7, c=11.\)

 

The sum of the roots is \(-\frac{b}{a}=-\frac{7}{2}\) and the product of the roots is \(\frac{c}{a}=\frac{11}{2}\).

 

Let's rewrite the expression:

\(ab + (a+b) = \frac{11}{2} - \frac{7}{2} = \boxed{2}.\)

 Feb 20, 2021

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