The function f(x) has 2 distinct real roots if and only if
the discriminant delta is strictly positive.
delta = b^2 -
4ac
We'll identify a, b and
c.
a = m
b = m -
1
c = 2 - m
delta = (m-1)^2 -
4*m*(2 - m)
We'll impose the constraint: delta >
0
(m-1)^2 - 4*m*(2 - m) >
0
We'll expand the square and remove the
brackets:
m^2 - 2m + 1 - 8m + 4m^2 >
0
We'll combine like
terms:
5m^2 - 10m +
1>0
Now, we'll determine the roots of the expression
5m^2 - 10m + 1.
5m^2 - 10m + 1 =
0
We'll apply the quadratic
formula:
m1 =
[10+sqrt(100-20)]/10
m1 =
(10+4sqrt5)/10
m1 =
(5+2sqrt5)/5
m2 =
(5-2sqrt5)/5
The expression is positive
outside the roots, namely when m belongs to the
intervals:
(-infinite ,
(5-2sqrt5)/5) U ((5+2sqrt5)/5 , +infinite).
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