Question
Question: If two roots of the equation x<sup>3</sup> – px<sup>2</sup> + qx – r = 0 are equal in magnitude but ...
If two roots of the equation x3 – px2 + qx – r = 0 are equal in magnitude but opposite in sign then:
A
pr = q
B
qr = p
C
pq = r
D
None of these
Answer
pq = r
Explanation
Solution
x3 – px2 + qx – r = 0
a + b – b = p Ž a = p
root satisfies the equation
a3 –pa2 + 9a – r = 0
p3 – p3 + pq – r = 0 Ž pq = r