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# A-Level Differentiation Question (i think) Watch

1. The Curve y= (10/2x+1) -2 intersects the x-axis at A, The tangent to the curve at A intersects the y-axis at C.

i) Show that the equation of AC is 5y + 4x = 8
ii) Find the distance AC

do i differentiate it twice?
2. Have you found the point A? Have you found the equation of the tangent?

You need to say where you're up to in the question or I can only guess why you're stuck.
3. i just differentiate y and got stuck there
4. (Original post by Candit)
The Curve y= (10/2x+1) -2 intersects the x-axis at A, The tangent to the curve at A intersects the y-axis at C.

i) Show that the equation of AC is 5y + 4x = 8
ii) Find the distance AC

do i differentiate it twice?
The equation you have written is ambiguous.

Do you mean
5. yes
6. (Original post by Candit)
The Curve y= (10/2x+1) -2 intersects the x-axis at A, The tangent to the curve at A intersects the y-axis at C.

i) Show that the equation of AC is 5y + 4x = 8
ii) Find the distance AC

do i differentiate it twice?
Part (a),

Set y=0, to find the x-coordinate of A.
Differentiate y = 10/(2x+1) -2 and sub in the x-coordinate of A, to get the gradient at A.
Use the coordinates of A and the gradient obtained to find the equation of tangent at A.
Set x=0 in the equation of tangent at A, to find the y-coordinate of point C.

Now find the gradient of AC, by using , then form an equation.
7. umm ok get it thanks alot

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Updated: June 10, 2012
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