Question

the mean of X + Y observation x- y find the sum of all observations

Answer 1

ANSWER:
Mean =Sum of observayion /total number of observation.
x-y=Sum of observation/x+y.
Sum of observation=(x-y)*(x+y)
Sum of observation=x^2-y^2 .

Answer 2

let us consider sum of observation as z

z÷x+y=x-y

z=(x+y)(x-y)

=xsquare+y square

hope its help you

thanx and be brainly...........................................