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  1. If   x2 = y + z, y2 = z + x, z2 = x + y,
    then the value of
    1
    +
    1
    +
    1
      is;
    x + 1x + 1z + 1
    1. –1
    2. 1
    3. 2
    4. 4
Correct Option: B

Tricky Approach
x2 = y + z
⇒  x2 + x = x + y + z
⇒  x (x + 1) = x + y + z ....(i)
Similarly,
y (y + 1) = x + y + z    .........(ii)
and, z (z + 1) = x + y + z    ...(iii)

∴ 
1
+
1
+
1
x + 1x + 1z + 1

=
x
+
y
+
z
x + y + zx + y + zz + y + z

⇒ 
x + y + z
= 1
x + y + z



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