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If $x + y + z = 9$ and $x y + yz + z x = 26$ , find $x^{2} + y^{2} + z^{2}$ .

Class 9Algebraic IdentitiesPolynomials

A55
B133
C81
D29

Step-by-Step Solution

x^{2} + y^{2} + z^{2} = (x + y + z)^{2} - 2 (x y + yz + z x) = 81 - 52 = 29

. (55 subtracts 26 only once.)

Answer: D) 29

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