Cases

H 0

H 1

H 2

H 3

R h v

No. of sign change

No. of positive real roots

1

+

+

+

+

R h v < 1

0

0

1

+

+

+

R h v > 1

1

1

2

+

+

+

R h v < 1

2

0, 2

2

+

+

R h v > 1

1

1

3

+

+

R h v < 1

2

0, 2

3

+

R h v > 1

1

1

4

+

+

+

R h v < 1

2

0, 2

4

+

+

R h v > 1

3

1, 3