Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Applications of Derivatives

Question:

The angle formed by the abscissa and the tangent to the parabola $y=x^2+4 x-17$ at the point $\frac{5}{2},-\frac{3}{4}$ is

Options:

$\tan ^{-1} 2$

$\tan ^{-1} 5$

$\tan ^{-1} 7$

None of these

Correct Answer:

None of these

Explanation:

Slope of x-axis is 0.

$y=x^2+4 x-17 \Rightarrow \frac{d y}{d x}=2 x+4$

∴  slope of tangent to parabola at $P\left(\frac{5}{2},-\frac{3}{4}\right)$

$=2\left(\frac{5}{2}\right)+4=9$

If $\theta$ is the angle between x-axis and the tangent at P then $\tan \theta=9 \Rightarrow \tan ^{-1} 9$.