If the roots of the equation x
2
−px+54=0 are in the ratio 2:3, then the value of p is
- A18
- B51
- C-21
- D15
Solution & Step-by-step Explanation
Let the roots of the quadratic equation x
2
−px+54=0 be α and β.
Given that the ratio of roots is α:β=2:3, we can define the roots as:
α=2kandβ=3k
From the standard relationships of a quadratic equation:
Product of roots:
α×β=
a
c
⟹(2k)×(3k)=54
6k
2
=54
k
2
=9⟹k=±3
Sum of roots:
α+β=−
1
(−p)
=p
2k+3k=p⟹5k=p
Case 1: If k=3, then p=5(3)=15.
Case 2: If k=−3, then p=5(−3)=−15.
Looking at the options provided, 15 is present in option D.
2
−px+54=0 be α and β.
Given that the ratio of roots is α:β=2:3, we can define the roots as:
α=2kandβ=3k
From the standard relationships of a quadratic equation:
Product of roots:
α×β=
a
c
⟹(2k)×(3k)=54
6k
2
=54
k
2
=9⟹k=±3
Sum of roots:
α+β=−
1
(−p)
=p
2k+3k=p⟹5k=p
Case 1: If k=3, then p=5(3)=15.
Case 2: If k=−3, then p=5(−3)=−15.
Looking at the options provided, 15 is present in option D.