If 2z = x + y, then the value of xx-z + yy-z is:
Explanation:
Given, 2z = x + y ⇒ z - x = y - z
Now xx-z + yy-z = xx-z + yz-x
⇒ xx-z + yy-z = xx-z - yx-z
⇒ xx-z + yy-z = x-yx-z
⇒ xx-z + yy-z = x-yx-(x+y)2 = 2
∴ xx-z + yy-z = 2
Alternately, Assume x = 2 and y = 4, hence z = 3
Now, xx-z + yy-z = 22-3 + 44-3 = -2 + 4 = 2
Hence, option (c).
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