Question Details

Options

A

There is no real value of x satisfying the above equation.

B

There is one positive and one negative real value of x satisfying the abov eequation

C

There is two rea positive value of x satisfying the above equation.

D

There is two rea negative value of x satisfying the above equation.

Show Answer

Correct Answer :

Option B

There is one positive and one negative real value of x satisfying the abov eequation

Solution :

The correct option is: There is one positive and one negative real value of x satisfying the abov eequation

Step-by-Step Explanation:

From the given image, we have the equation:
tan - 1 2 3 - x + 1 = cot - 1 3 3 x + 1

First, recall the relationship between the inverse trigonometric functions: for any y > 0,
cot - 1 ( y ) = tan - 1 1 y

Since 3x > 0 for all real numbers x, the argument of the cotangent function is always positive:
3 3 x + 1 > 0

We can rewrite the right-hand side of our equation as:
cot - 1 3 3 x + 1 = tan - 1 3 x + 1 3

Now, equating the arguments of the arctangent functions from both sides of the equation yields:
2 3 - x + 1 = 3 x + 1 3

We simplify the term 3-x + 1 on the left side of the equation:
3 - x + 1 = 1 3 x + 1 = 1 + 3 x 3 x

Substituting this back into the equation, we get:
2 · 3 x 3 x + 1 = 3 x + 1 3

Cross-multiplying the denominators, we obtain:
6 · 3 x = 3 x + 1 2

Let y = 3x. Since x must be a real number, y must be strictly positive (y > 0). Substituting y into the equation gives:
6 y = y + 1 2

Expanding the squared term and rearranging the equation into standard quadratic form:
6 y = y 2 + 2 y + 1
y 2 - 4 y + 1 = 0

Applying the quadratic formula to solve for y:
y = - - 4 ± - 4 2 - 4 · 1 · 1 2 · 1
y = 4 ± 12 2 = 2 ± 3

Since √3 ≈ 1.732, both solutions for y are positive:
1. y1 = 2 + √3 ≈ 3.732 > 0
2. y2 = 2 - √3 ≈ 0.268 > 0

Now we solve for the corresponding real values of x using 3x = y:
For y1 = 2 + √3:
3 x = 2 + 3
Since 2 + √3 > 1, the exponent x = log3(2 + √3) is positive (x > 0).

For y2 = 2 - √3:
3 x = 2 - 3
Since 0 < 2 - √3 < 1, the exponent x = log3(2 - √3) is negative (x < 0).

Consequently, there is exactly one positive and one negative real value of x that satisfies the equation.

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