Let a
b be two non-zero real numbers. Then the number of elements in the set X = {z
C: Re(az 2 + bz) = a and Re(bz 2 + az) = b} is equal to
Text Solution
Verified by ExpertsA
Given,
X = {z
C : Re(az 2 + bz)= a and Re(bz 2 + az)= b}
Now, let z = x + iy
So, Re (az 2 + bz) = a
Ref a (x + iy) 2 + b(x+iy) = a
Re (a (x 2 - y 2 + 2ixy) + b (x + iy)) = a
a (x 2 - y 2 ) + bx = a ... (i)
And, Re(bz 2 +az) = b
Re (b (x + iy) 2 + a (x + iy)) = b
Re (b (x 2 - y 2 + 2ixy) + a (x + iy) = b
b (x 2 -y 2 ) + ax = b ... (ii)
From (i) and (ii), (i) -(ii)
we get, (x 2 - y 2 ) (a - b)-x (a - b) = a - b
X 2 – y 2 - X = 1 . . . (iii)
From (i) and (ii), (i)+(ii)
((x 2 - y 2 )+x - l) (a + b)= 0 (Note: here a + b
0 is considered but it is not clear from the question)
x 2 - y 2 + x - 1 = 0 ... (iv)
Now from (iii) and (iv) we get,
x = 0, y 2 = -1 (No solution)
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