Question

Expansion of $(x + y + z)^{2}$ :

x^{2} + y^{2} + z^{2} + 2 (x y + y z + z x)

x^{2} + y^{2} + z^{2} - 2 (x y + y z + z x)

x^{2} + y^{2} + z^{2} - 2 (x y - y z + z x)

x^{2} + y^{2} + z^{2} + 2 (x y - y z + z x)

Solution

The correct option is A $x^{2} + y^{2} + z^{2} + 2 (x y + y z + z x)$
Use identity
$(a + b + c)^{2} = a^{2} + b^{2} + c^{2} + 2 (a b + b c + c a)$

Mathematics

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