Home
Class 12
MATHS
Find the equation of the tangent to the ...

Find the equation of the tangent to the curve `y=(x^3-1)(x-2)` at the points where the curve cuts the x-axis.

Text Solution

AI Generated Solution

The correct Answer is:
To find the equation of the tangent to the curve \( y = (x^3 - 1)(x - 2) \) at the points where it cuts the x-axis, we will follow these steps: ### Step 1: Find the points where the curve cuts the x-axis The curve cuts the x-axis where \( y = 0 \). Therefore, we set the equation to zero: \[ (x^3 - 1)(x - 2) = 0 \] This gives us two factors to solve: 1. \( x^3 - 1 = 0 \) 2. \( x - 2 = 0 \) From \( x - 2 = 0 \), we get: \[ x = 2 \] From \( x^3 - 1 = 0 \), we can factor it as: \[ x^3 - 1 = (x - 1)(x^2 + x + 1) = 0 \] The real root from this factorization is: \[ x = 1 \] The quadratic \( x^2 + x + 1 \) has no real roots (its discriminant is negative). Therefore, the curve cuts the x-axis at \( x = 1 \) and \( x = 2 \). ### Step 2: Identify the points on the curve The points where the curve intersects the x-axis are: 1. \( (1, 0) \) 2. \( (2, 0) \) ### Step 3: Differentiate the curve to find the slope To find the slope of the tangent at these points, we need to differentiate \( y \): \[ y = (x^3 - 1)(x - 2) \] Using the product rule: \[ \frac{dy}{dx} = (x^3 - 1) \cdot \frac{d}{dx}(x - 2) + (x - 2) \cdot \frac{d}{dx}(x^3 - 1) \] Calculating the derivatives: \[ \frac{d}{dx}(x - 2) = 1 \] \[ \frac{d}{dx}(x^3 - 1) = 3x^2 \] Substituting back into the derivative: \[ \frac{dy}{dx} = (x^3 - 1)(1) + (x - 2)(3x^2) \] \[ = x^3 - 1 + 3x^2(x - 2) \] \[ = x^3 - 1 + 3x^3 - 6x^2 \] \[ = 4x^3 - 6x^2 - 1 \] ### Step 4: Calculate the slope at the points \( (1, 0) \) and \( (2, 0) \) 1. **At \( (1, 0) \)**: \[ \frac{dy}{dx} \bigg|_{x=1} = 4(1)^3 - 6(1)^2 - 1 = 4 - 6 - 1 = -3 \] 2. **At \( (2, 0) \)**: \[ \frac{dy}{dx} \bigg|_{x=2} = 4(2)^3 - 6(2)^2 - 1 = 32 - 24 - 1 = 7 \] ### Step 5: Write the equations of the tangents Using the point-slope form of the line \( y - y_1 = m(x - x_1) \): 1. **For the point \( (1, 0) \)** with slope \( -3 \): \[ y - 0 = -3(x - 1) \] \[ y = -3x + 3 \] 2. **For the point \( (2, 0) \)** with slope \( 7 \): \[ y - 0 = 7(x - 2) \] \[ y = 7x - 14 \] ### Final Answer The equations of the tangents to the curve at the points where it cuts the x-axis are: 1. \( y = -3x + 3 \) 2. \( y = 7x - 14 \)

To find the equation of the tangent to the curve \( y = (x^3 - 1)(x - 2) \) at the points where it cuts the x-axis, we will follow these steps: ### Step 1: Find the points where the curve cuts the x-axis The curve cuts the x-axis where \( y = 0 \). Therefore, we set the equation to zero: \[ (x^3 - 1)(x - 2) = 0 \] ...
Promotional Banner

Topper's Solved these Questions

  • STRAIGHT LINE IN SPACE

    RD SHARMA|Exercise Solved Examples And Exercises|134 Videos
  • THE PLANE

    RD SHARMA|Exercise Solved Examples And Exercises|301 Videos

Similar Questions

Explore conceptually related problems

Find the equation of the tangents to the curve y=(x-1)(x-2) at the points where the curve cuts the x-axis.

Find the equation of the tangent to the curve y=(x-7)/((x-2(x-3)) at the point where it cuts the x-axis.

Equation of the tangent to the curve y=1-e^((x)/(2)) at the point where the curve cuts y -axis is

Equation of the tangent to the curve y=2-3x-x^(2) at the point where the curve meets the Y -axes is

The equation of the tangent to the curve y=e^(-|x|) at the point where the curve cuts the line x = 1, is

Equations of tangents to the curve y=x-(1)/(x) at the points where the curve meets the X- axes are

Find the equation of the tangent of the curve y=3x^(2) at (1, 1).

Write the equation of the tangent to the curve y=x^2-x+2 at the point where it crosses the y-axis.

Find the equation of the tangent to the curve y=sec x at the point (0,1)

RD SHARMA-TANGENTS AND NORMALS-Solved Examples And Exercises
  1. Find all the tangents to the curve y=cos(x+y),-2pilt=xlt=2pi that are ...

    Text Solution

    |

  2. Find the equation of the normal to the curve y=(1+x)^y+sin^(-1)(sin^2x...

    Text Solution

    |

  3. Find the equation of the tangent to the curve y=(x^3-1)(x-2) at the po...

    Text Solution

    |

  4. Show that the line x/a+y/b=1 touches the curve y=b e^(-x/a) at the p...

    Text Solution

    |

  5. Find the equations of tangent and normal to the ellipse (x^2)/(a^2)+(y...

    Text Solution

    |

  6. Find the equation of the normal to the curve y=2x^2+3sinx at x=0.

    Text Solution

    |

  7. Find the coordinates of the points on the curve y=x^2+3x+4, the tangen...

    Text Solution

    |

  8. Find the equations of the tangents drawn to the curve y^2-2x^2-4y+8=0....

    Text Solution

    |

  9. Find the equation(s) of normal(s) to the curve 3x^2-y^2=8 which is (ar...

    Text Solution

    |

  10. Find the equation of the tangent line to the curve y=sqrt(5x-3)-2 whic...

    Text Solution

    |

  11. Find the points on the curve 4x^2+9y^2=1 , where the tangents are perp...

    Text Solution

    |

  12. Find the points on the curve 9y^2=x^3 where normal to the curve makes ...

    Text Solution

    |

  13. Prove that the curves x y=4 and x^2+y^2=8 touch each other.

    Text Solution

    |

  14. Prove that the curves y^2=4x and x^2+y^2-6x+1=0 touch each other at th...

    Text Solution

    |

  15. Show that the angle between the tangent at any point P and the line jo...

    Text Solution

    |

  16. Find the slopes of the tangent and the normal to the curve x^2+3y y2=5...

    Text Solution

    |

  17. Show that the tangents to the curve y=x^3-3 at the points where x=2 a...

    Text Solution

    |

  18. Prove that the tangents to the curve y=x^2-5+6 at the points (2,0)a n ...

    Text Solution

    |

  19. The slope of the curve 2y^2=a x^2+ba t(1,-1) is -1 Find a , b

    Text Solution

    |

  20. Find the points on the curve y=x^3-2x^2-x at which the tangent lines a...

    Text Solution

    |