Answer in Brief
If x2 + y2 = 29 and xy = 2, find the value of x + y.
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Solution
We have:
\[\left( x + y \right)^2 = x^2 + 2xy + y^2 \]
\[ \Rightarrow \left( x + y \right) = \pm \sqrt{x^2 + 2xy + y^2}\]
\[ \Rightarrow \left( x + y \right) = \pm \sqrt{29 + 2 \times 2} ( \because x^2 + y^2 = 29 \text { and } xy = 2)\]
\[ \Rightarrow \left( x + y \right) = \pm \sqrt{29 + 4}\]
\[ \Rightarrow \left( x + y \right) = \pm \sqrt{33}\]
Concept: Algebraic Expressions
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