The equation of tangent to the curve y = x2 + 4x + 1 at (-1, - 2) is 

  1. 2x - y = 0
  2. 2x + y - 5 = 0
  3. 2x - y - 1 = 0
  4. x + y - 1 = 0

Answer (Detailed Solution Below)

Option 1 : 2x - y = 0
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Army Havildar SAC - Quick Quiz
5 Qs. 10 Marks 6 Mins

Detailed Solution

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Concept:

To determine the equation of a tangent to a curve:

Step. 1) Find the derivative of given curve 

Step. 2) Calculate the gradient of the tangent at given point.

Step. 3)  Determine the equation of tangent.

Substitute the gradient of the tangent and the coordinates of the given point into the gradient-point form of the straight line equation .

Calculations:

  Given equation of curve is y = x2 + 4x + 1.

 

 Step. 1) Find the derivative of given curve

Differentiate w.r.to x on both side, we get

Step. 2) Calculate the gradient of the tangent at given point

To determine the gradient of the tangent at the point (-1, -2), put x  = -1 into the equation for the derivative.(1;3) m , we substitute th

 

⇒ m =2 (- 1) + 4 

⇒ m = 2 

Step. 3)  Determine the equation of tangent.

Substitute the gradient of the tangent and the coordinates of the given point into the gradient-point form of the straight line equation.

⇒ (y +2) = 2(x+ 1)

⇒ 2x - y = 0

Hence, the equation of tangent to the curve y = x2 + 4x + 1 at (-1, -2) is  2x - y = 0

 

Latest Army Havildar SAC Updates

Last updated on Jul 1, 2025

-> The Indian Army has released the Exam Date for Indian Army Havildar SAC (Surveyor Automated Cartographer).

->The Exam will be held on 9th July 2025.

-> Interested candidates had applied online from 13th March to 25th April 2025.

-> Candidates within the age of 25 years having specific education qualifications are eligible to apply for the exam.

-> The candidates must go through the Indian Army Havildar SAC Eligibility Criteria to know about the required qualification in detail. 

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