# Sketching Curves - C1 - Chapter 4

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#1

How do you work out the equation of a curve using its points of intersection
0
4 years ago
#2
(Original post by Chittesh14)

How do you work out the equation of a curve using its points of intersection
Intersection with what?

Please post a question that you're stuck with. 0
#3
(Original post by SeanFM)
Intersection with what?

Please post a question that you're stuck with. Part c

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0
4 years ago
#4
(Original post by Chittesh14)

Part c

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Think about the information that you've been given in the question and then what you've found in part b.
1
4 years ago
#5
(x-A)(x-B)=0
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#6
(Original post by ubisoft)
(x-A)(x-B)=0
I kind of understand that a bit.
What would A and B be in that equation. They both have two coordinates, x and y coordinates. What is A in the bracket and what is B in the other bracket?

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0
4 years ago
#7
(Original post by Chittesh14)
I kind of understand that a bit.
What would A and B be in that equation. They both have two coordinates, x and y coordinates. What is A in the bracket and what is B in the other bracket?

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The x coordinate of the intercept. The y intercept is 0 for both as it's the x intercept.
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#8
(Original post by ubisoft)
(x-A)(x-B)=0
If you are trying to say (x+3)(x-2)=0,

I understand that, but when I expand it, I get a different answer to the actual answer.

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#9
(Original post by ubisoft)
The x coordinate of the intercept. The y intercept is 0 for both as it's the x intercept.
Sorry, I think I understood the part above, just it didn't give me the answer? Posted from TSR Mobile
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#10
(Original post by ubisoft)
The x coordinate of the intercept. The y intercept is 0 for both as it's the x intercept.
Maybe, the answer in the book is incorrect.
The answer in the book is x^2 + 2x - 5

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0
4 years ago
#11
(Original post by Chittesh14)
Maybe, the answer in the book is incorrect.
The answer in the book is x^2 + 2x + 5

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which part?
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#12
(Original post by TeeEm)
which part?
C

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1
4 years ago
#13
(Original post by Chittesh14)
Maybe, the answer in the book is incorrect.
The answer in the book is x^2 + 2x + 5

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The correct answer for part c is . The book has the wrong answer.
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4 years ago
#14
if you have the coordinates of A and B

use A first
substitute the x and the y coordinate of A into the quadratic and you will get a linear equation in p and q.

then you substitute the x and the y coordinate of B into the quadratic and you will get a second linear equation in p and q.

you solve simultaneously to get p and q
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#15
(Original post by TeeEm)
if you have the coordinates of A and B

use A first
substitute the x and the y coordinate of A into the quadratic and you will get a linear equation in p and q.

then you substitute the x and the y coordinate of B into the quadratic and you will get a second linear equation in p and q.

you solve simultaneously to get p and q
I was actually planning to do that, but I thought it'll be incorrect lol.

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#16
Sorry, I thought I edited the typo. The book answer was x^2 + 2x - 5.

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#17
(Original post by TeeEm)
if you have the coordinates of A and B

use A first
substitute the x and the y coordinate of A into the quadratic and you will get a linear equation in p and q.

then you substitute the x and the y coordinate of B into the quadratic and you will get a second linear equation in p and q.

you solve simultaneously to get p and q

I'm kind of confused here.

I've got two equations when I substituted the values from the A and the B coordinates.

A: -11 = px + q
B: -1 = px + q

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0
4 years ago
#18
(Original post by Chittesh14)
I'm kind of confused here.

I've got two equations when I substituted the values from the A and the B coordinates.

A: -11 = px + q
B: -1 = px + q

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there should be no x, x was substituted with the x from each of the 2 coordinates from A and B
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#19
(Original post by TeeEm)
there should be no x, x was substituted with the x from each of the 2 coordinates from A and B
Oops, I've done it now.
Q = -5 and p = 2

X^2 + 2x - 5

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#20
Thanks everyone Posted from TSR Mobile
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