if a, b are the roots of x^2 - 3x + p =0 and c, d are the roots of x^2 - 12x +q = 0 where a,b,c,d form a G.P, find the ratio of (q+p):(q-p)
It is given that a and b are the roots of x2 – 3x + p = 0
a + b = 3 and ab = p … (1)
Also, c and d are the roots of
c + d = 12 and cd = q … (2)
It is given that a, b, c, d are in G.P.
Let a = x, b = xr, c = xr2, d = xr3
From (1) and (2), we obtain
x + xr = 3
x (1 + r) = 3
xr2 + xr3 =12
xr2 (1 + r) = 12
On dividing, we obtain
When r = 2 and x =1,
ab = x2r = 2
cd = x2r5 = 32
similarly when r = -2 & x = -3 wecan do it by getting same result