Answer :
A/d is equal to c/b if a, b, c, and d are positive real numbers that form an increasing arithmetic sequence and a, b, d, a geometric sequence.
Since a, b, c, d form an increasing arithmetic sequence, we can write them as
a = x,
b = x + d,
c = x + 2d
Also, since a, b, d form a geometric sequence, we have
a = bx, d = b2
Substituting the values in the equation for c and d, we get
c = x + 2b2
Now, dividing both sides by b, we get
a/d = c/b
=> a/d = (x + 2b2)/b
=> a/d = x/b + 2b
=> a/d = c/b
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