Question Details

Read the following quadric equation carefully and answer the questions given below.

Equation 1: a 2 7 a + d = 0

Equation 2: b 2 4 b + ( d 9 ) = 0

Note: Roots of the equation 1 are ‘x’ and ‘y’ and the roots of equation 2 are ‘x’ and ‘y – x’ .


If we multiply equation 2 by 3z and add 1 in the smallest root of the equation newly formed, then find the resultant number?

Options

A

4

B

3

C

2

D

0

E

None of the above

Show Answer

Correct Answer :

Option C

2

2

Solution :

The correct answer is 2.

Let us solve the problem step-by-step:

Step 1: Understand the roots of the given equations using Vieta's formulas

We are given Equation 1:
a 2 7 a + d = 0
The roots of Equation 1 are given as x and y. Using the relationship between roots and coefficients (Vieta's formulas):
Sum of roots: x + y = 7 (Equation A)
Product of roots: x y = d (Equation B)

We are also given Equation 2:
b 2 ��� 4 b + ( d 9 ) = 0
The roots of Equation 2 are given as x and (y - x). Using Vieta's formulas:
Sum of roots: x + ( y x ) = y = 4 (Equation C)
Product of roots: x ( y x ) = d 9 (Equation D)

Step 2: Find the values of x, y, and the roots of Equation 2

From Equation C, we have:
y = 4

Substitute y = 4 into Equation A:
x + 4 = 7 x = 3

Now, we can find the roots of Equation 2:
First root = x = 3
Second root = y x = 4 3 = 1
The roots of Equation 2 are 3 and 1. The smallest root of Equation 2 is 1.

Step 3: Analyze the effect of multiplying the equation by 3z

When we multiply a quadratic equation of the form f ( b ) = 0 by a non-zero constant 3 z , the newly formed equation is:
3 z [ b 2 4 b + ( d 9 ) ] = 0
Since 3 z 0 for all real values of z, the roots of the equation remain completely unchanged.
Therefore, the roots of the newly formed equation are still 1 and 3, and the smallest root remains 1.

Step 4: Find the final resultant number

Adding 1 to the smallest root of the newly formed equation:
1 + 1 = 2

Thus, the resultant number is 2.

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