Question Details

The equations  3 x2 5x + p = 0 and  2 x2 2x + q = 0 have one common root. The sum of the other roots of this equa

Options

A

8 3 p + 3 2 q

B

2 3 p + 3 2 q

C

8 3 + p + 1 3 q

D

2 3 2p + 2 3 q

Show Answer

Correct Answer :

Option A

8 3 p + 3 2 q

Solution :

The correct option is 8 3 p + 3 2 q .

Let's find the sum of the other roots step-by-step. First, let the common root of the two given quadratic equations be α. Let the other root of the first equation be β and the other root of the second equation be γ.

For the first quadratic equation:

3 x2 5x + p = 0

Using Vieta's formulas, the sum of its roots is given by the negative coefficient of x divided by the coefficient of x2:

α + β = 53

For the second quadratic equation:

2 x2 2x + q = 0

The sum of its roots is:

α + γ = 22 = 1

We are asked to find the sum of the other roots, which is β+γ. From the sum of roots equations, we can express β and γ in terms of α:

β = 53 α

γ = 1 α

Adding these together gives us the expression we want to evaluate:

β + γ = (53α) + (1α) = 83 2α

Now, we need to find the value of 2α in terms of p and q. Since α is a common root, it must satisfy both original equations:

3α2 5α + p = 0    (Equation 1)

2α2 2α + q = 0    (Equation 2)

To eliminate the α2 term, we can multiply Equation 2 by 32:

32 (2α22α+q) = 0

3α2 3α + 3q2 = 0    (Equation 3)

Next, we subtract Equation 3 from Equation 1:

(3α25α+p) (3α23α+3q2) = 0

2α + p 3q2 = 0

Rearranging this to solve for 2α:

2α = p + 3q2

Finally, we substitute this back into our expression for β+γ:

β + γ = 83 2α

β + γ = 83 p + 32 q

This matches our correct option perfectly.

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