1.

If x, y, z are in A.P. and A1is the A.M. of x and y, and A2 is the A.M. of y and z, then prove that the A.M. of A1 and A2 is y.

Answer»

Given that,

A1 = AM of x and y

And A2 = AM of y and z

So, A1 = (x + y)/2

A2 = (y + x)/2

AM of A1 and A2 = (A1 + A2)/2

= [(x + y)/2 + (y + z)/2]/2

= [x + y + y + z]/2

= [x + 2y + z]/2

Since x, y, z are in AP, y = (x + z)/2

AM = [(x + z/2) + (2y/2)]/2

= (y + y)/2

= 2y/2

= y

Hence proved.



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