# Relationships and calculusWatch

#1
The function f is defined by f(x) = 8-2(x-4) ^2. The graph of y=f(x) intersects the x-axis at A and B. Determine the equation of the tangent at B using differentiation. How to solve this?
Last edited by Thansi; 1 week ago
0
1 week ago
#2
So what do you need to find the equation of a line? Y=mx+c. And you need to know B, how do you first x-axis intercepts/roots?
1
1 week ago
#3
(Original post by Thansi)
The function f is defined by f(x) = 8-2(x-4) ^2. The graph of y=f(x) intersects the x-axis at A and B. Determine the equation of the tangent at B. How to solve this?
Kind of an ambiguous questions considering you don't know which root corresponds to A and which root corresponds to B.
0
1 week ago
#4
should be in Relationships....

wait
0
1 week ago
#5
As RDK said, the question is ambiguous in the definition of roots A and B, is there more information in the question that you haven't mentioned? A condition on one of the roots being above a certain number?

Your general plan here regardless, is to solve f(x) = 0, to find the two points where it intersects the x-axis, one of those x values will correspond to the root B. Then differentiate the function and substitute that value of x to get the gradient of the tangent. Your coordinates are (B,0), how do you find the equation of a line given the gradient, and coordinates that it passes through?
0
#6
(Original post by Thansi)
The function f is defined by f(x) = 8-2(x-4) ^2. The graph of y=f(x) intersects the x-axis at A and B. Determine the equation of the tangent at B using differentiation. How to solve this?
0
#7
(Original post by RDKGames)
Kind of an ambiguous questions considering you don't know which root corresponds to A and which root corresponds to B.
Sorry, there were an error in uploading image of the full question.
Thanks for helping me.
Last edited by Thansi; 1 week ago
0
X

new posts
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• University of the West of England, Bristol
Wed, 23 Jan '19
• University of East London
Wed, 23 Jan '19
• University of Gloucestershire
School of Education Open Day Postgraduate
Wed, 23 Jan '19

### Poll

Join the discussion

Remain (1462)
79.59%
Leave (375)
20.41%