Find normal line equation

Use the negative reciprocal of the gradient at a point to find the equation of the normal line.

6 questions · Standard +0.0

1.07m Tangents and normals: gradient and equations
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CAIE P1 2017 November Q10
11 marks Moderate -0.3
10 \includegraphics[max width=\textwidth, alt={}, center]{518bb805-5b14-4b41-94fd-38a31a90c218-18_551_689_260_726} The diagram shows part of the curve \(y = \sqrt { } ( 5 x - 1 )\) and the normal to the curve at the point \(P ( 2,3 )\). This normal meets the \(x\)-axis at \(Q\).
  1. Find the equation of the normal at \(P\).
  2. Find, showing all necessary working, the area of the shaded region.
Edexcel C3 2006 January Q3
5 marks Moderate -0.3
3. The point \(P\) lies on the curve with equation \(y = \ln \left( \frac { 1 } { 3 } x \right)\). The \(x\)-coordinate of \(P\) is 3 . Find an equation of the normal to the curve at the point \(P\) in the form \(y = a x + b\), where \(a\) and \(b\) are constants.
(5)
OCR C3 Q8
13 marks Standard +0.3
8. The curve \(C\) has the equation \(y = \sqrt { x } + \mathrm { e } ^ { 1 - 4 x } , x \geq 0\).
  1. Find an equation for the normal to the curve at the point \(\left( \frac { 1 } { 4 } , \frac { 3 } { 2 } \right)\). The curve \(C\) has a stationary point with \(x\)-coordinate \(\alpha\) where \(0.5 < \alpha < 1\).
  2. Show that \(\alpha\) is a solution of the equation $$x = \frac { 1 } { 4 } [ 1 + \ln ( 8 \sqrt { x } ) ]$$
  3. Use the iterative formula $$x _ { n + 1 } = \frac { 1 } { 4 } \left[ 1 + \ln \left( 8 \sqrt { x _ { n } } \right) \right]$$ with \(x _ { 0 } = 1\) to find \(x _ { 1 } , x _ { 2 } , x _ { 3 }\) and \(x _ { 4 }\), giving the value of \(x _ { 4 }\) to 3 decimal places.
  4. Show that your value for \(x _ { 4 }\) is the value of \(\alpha\) correct to 3 decimal places.
  5. Another attempt to find \(\alpha\) is made using the iterative formula $$x _ { n + 1 } = \frac { 1 } { 64 } \mathrm { e } ^ { 8 x _ { n } - 2 }$$ with \(x _ { 0 } = 1\). Describe the outcome of this attempt.
CAIE P1 2024 November Q10
10 marks Standard +0.3
A function f with domain \(x > 0\) is such that \(\mathrm{f}'(x) = 8(2x - 3)^{\frac{1}{3}} - 10x^{\frac{3}{5}}\). It is given that the curve with equation \(y = \mathrm{f}(x)\) passes through the point \((1, 0)\).
  1. Find the equation of the normal to the curve at the point \((1, 0)\). [3]
  2. Find f\((x)\). [4]
It is given that the equation \(\mathrm{f}'(x) = 0\) can be expressed in the form $$125x^2 - 128x + 192 = 0.$$
  1. Determine, making your reasoning clear, whether f is an increasing function, a decreasing function or neither. [3]
Edexcel C2 Q5
10 marks Standard +0.3
The curve \(C\) with equation \(y = p + qe^x\), where \(p\) and \(q\) are constants, passes through the point \((0, 2)\). At the point \(P\) (ln 2, \(p + 2q\)) on \(C\), the gradient is 5.
  1. Find the value of \(p\) and the value of \(q\). [5]
The normal to \(C\) at \(P\) crosses the \(x\)-axis at \(L\) and the \(y\)-axis at \(M\).
  1. Show that the area of \(\triangle OLM\), where \(O\) is the origin, is approximately 53.8 [5]
WJEC Unit 3 2018 June Q16
11 marks Moderate -0.3
  1. Differentiate the following functions with respect to \(x\), simplifying your answer wherever possible.
    1. \(e^{3\tan x}\),
    2. \(\frac{\sin 2x}{x^2}\). [5]
  2. A function is defined implicitly by $$3x^2y + y^2 - 5x = 5.$$ Find the equation of the normal at the point \((1, 2)\). [6]