C) If m is selected at random from set {1,2,...10}
and the probability that the quadratic equation
2x2 + 2mx +m+1=0 has real roots is k, then
value of 5k is more than
Answers
Answered by
1
Step-by-step explanation:
2
+2mx+m+1=0 has real roots
⇒4m
2
≥4.2.(m+1)
⇒4m
2
−8m−8≥0
⇒m
2
−2m−2≥0
[m−(1−
m
)][m−(1+
3
)]≥0
⇒m≤(1−
3
) Or m≥(1−
3
)
m≤−0.73 Or m≥2.7
∴m=3,4,5,6,7,8,9,10
∴Probability k=
10
C
1
8
C
1
=
10
8
=
5
4
∴5k=4
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