A triangle is formed by the tangents to the curve \(\mathrm{f}(\mathrm{x})=\mathrm{x}^{2}+\mathrm{bx}-\mathrm{b}\) at the point \((1,1)\) and the coordinate axes, lies in the first Quadrant. If the area is 2, then value of \(b\) is : (a) \(-1\) (b) 3 (c) \(-3\) (d) 1

Short Answer

Expert verified
The value of \(b\) is not among the given options (a), (b), (c), or (d). The correct value for \(b\) is \(-1 + \sqrt{17}\).

Step by step solution

01

Calculate the equation of the tangent line

We'll find the equation of tangent by using the derivative of the curve and the point-slope form of a linear equation. The derivative of the given curve function is: \(f'(x) = 2x + b\) Now we'll need to find the slope of the tangent line at the point (1, 1): m = \(f'(1) = 2(1) + b = 2 + b\) Now, we'll use the point-slope form of the linear equation to write the tangent line equation: \(y - 1 = (2 + b)(x - 1)\)
02

Find the x-intercept and y-intercept of the tangent line

To find the x-intercept, we let y = 0: \(0 - 1 = (2 + b)(x - 1)\) Solving for x, we have: \(x = \frac{b + 1}{b + 2}\) To find the y-intercept, let x = 0: \(y - 1 = (2 + b)(0 - 1)\) Solving for y, we have: \(y = 1 - 2 - b = -1 - b\)
03

Determine the vertices of the triangle in the first quadrant

We now have the following vertices for the triangle: A (0, 0) - the origin. B \(\left(\frac{b + 1}{b + 2}, 0\right)\) - the x-intercept. C (0, -1 - b) - the y-intercept.
04

Write down the formula for the area of the triangle

We can calculate the area of the triangle using the vertices coordinates: Area = \(\frac{1}{2}\) × base × height Area = \(\frac{1}{2}\) × \(\frac{b + 1}{b + 2}\) × (-1 - b)
05

Set the area equal to 2 and solve for the value of \(b\)

Equate the area to 2: \(\frac{1}{2} \times \frac{b + 1}{b + 2} \times (-1 - b) = 2\) \( b(1 + b) = -2(b + 2) \) Expand and rearrange the equation: \(b^2 + b = -2b - 4\) \(b^{2} + 3b + 4 = 0\) Now, we'll solve for the values of \(\(b\)\): \(b = \frac{-3 \pm \sqrt{(-3)^{2}-4(4)}}{2}\) \(b = \frac{-3 \pm \sqrt{9 - 16}}{2}\) \(b = \frac{-3 \pm \sqrt{-7}}{2}\) There is no real solution for the equation, so we should recheck our reasoning about the triangle in the first quadrant. Upon rereading the problem, we see the area of the triangle is 2 and not the value of b. Thus, our equation for the area of the triangle should be: \(\frac{1}{2} \times \frac{b + 1}{b + 2} \times (-1 - b) = -2\) \( -2b(b + 1) = -4(b + 2) \) Now solving for b: \( 2b(b + 1) = 4(b + 2) \) \(2b^{2} + 2b = 4b + 8\) \(2b^{2} - 2b - 8 = 0\) Factoring the quadratic equation: \(2(b^{2} - b - 4) = 0\) Solving for b: \(b = \frac{1 \pm \sqrt{(-1)^{2}+4(4)}}{1}\) \(b = \frac{1 \pm \sqrt{17}}{1}\) However, since the triangle lies in the first quadrant, only the negative value will be valid: \(b = -1 + \sqrt{17}\) So, the value of b is not among the given options (a), (b), (c), or (d).

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Most popular questions from this chapter

For a \(+b+c=0\), the line \(3 \mathrm{ax}+4 \mathrm{by}+\mathrm{c}=0\) passes through the fixed point \(\ldots \ldots .\) (a) \([(1 / 3),-(1 / 4)]\) (b) \([-(1 / 3),(1 / 4)]\) (c) \([(1 / 3),(1 / 4)]\) (d) \([-(1 / 3),-(1 / 4)]\)

The equation of a line passing through \((4,3)\) and the sum of whose intercepts is \(-1\) is........ (a) \((\mathrm{x} / 2)+(\mathrm{y} / 3)=1,(\mathrm{x} / 2)+(\mathrm{y} / 1)]=1\) (b) \((\mathrm{x} / 2)+(\mathrm{y} / 3)=-1,[\mathrm{x} /(-2)]+(\mathrm{y} / 1)=1\) (c) \((\mathrm{x} / 2)+(\mathrm{y} / 3)=-1,\\{\mathrm{x} /(-2)\\}+(\mathrm{y} / 1)=-1\) (d) \((\mathrm{x} / 2)-(\mathrm{y} / 3)=1,\\{\mathrm{x} /(-2)\\}+(\mathrm{y} / 1)=1\)

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A line intersects \(\mathrm{X}\) -axis and Y-axis at \(\mathrm{A}\) and \(\mathrm{B}\) respectively. If \(\mathrm{AB}=15\) and \(\underline{\mathrm{AB}}\) makes a triangle of area 54 units with coordinate axes, then the equation of \(\underline{A B}\) is \(\ldots .\) (a) \(4 x \pm 3 y=36\) or \(3 x \pm 4 y=36\) (b) \(4 x \pm 3 y=24\) or \(3 x \pm 4 y=24\) (c) \(-4 \mathrm{x} \pm 3 \mathrm{y}=24\) or \(-3 \mathrm{x} \pm 4 \mathrm{y}=24\) (d) \(-4 x \pm 3 y=12\) or \(-3 x \pm 4 y=12\)

The image of origin in the line \(\mathrm{x}+4 \mathrm{y}=1 \mathrm{is}\) (a) \([(2 / 17),-(8 / 17)]\) (b) \([-(2 / 17),-(8 / 17)]\) (c) \([-(2 / 17),(8 / 17)]\) (d) \([(2 / 17),(8 / 17)]\)

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