78. If one root of the equation (1 - m) xº + Ix + 1 = 0 isdouble the

1.	78. If one root of the equation (1 - m) xº + Ix + 1 = 0 isdouble the other and lis real, then what is the greatestvalue of m?
Answer» Let the roots be r and 2r So, sum of roots= 3r = -l/(l-m).lProduct of roots= 2r^2 =1/(l-m) Equating them we get: 2l^2- 9l + 9m=0. For l to be real Discriminant, D>=0 So, 81 - 72m >= 0or, m< = 9/8 Therefore, greatest value of m = 9/8

78. If one root of the equation (1 - m) xº + Ix + 1 = 0 isdouble the other and lis real, then what is the greatestvalue of m?

Answer»

Let the roots be r and 2r

So, sum of roots= 3r = -l/(l-m).lProduct of roots= 2r^2 =1/(l-m)

Equating them we get: 2l^2- 9l + 9m=0. For l to be real Discriminant, D>=0

So, 81 - 72m >= 0or, m< = 9/8

Therefore, greatest value of m = 9/8