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# Maths Homework - help please ASAP watch

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1. a curve has equation y=3x(sqred) +6x-7. find the equation of the tangent to the curve at the point x=1, can you please explain what to do
2. (Original post by Misshussain23)
a curve has equation y=3x(sqred) +6x-7. find the equation of the tangent to the curve at the point x=1, can you please explain what to do
Differentiate to get the gradient function for the curve. Hence find the gradient of the curve at x = 1. Then use either or to find the equation of the tangent.

3. Is this right?

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4. It's perfect except for when you go from the penultimate to the final line, you've made a silly algebra mistake :-)
5. (Original post by 16Characters....)
It's perfect except for when you go from the penultimate to the final line, you've made a silly algebra mistake :-)
okay thankyou, i will have amend that

6. I'm not sure how you find x and y for part a 😬 can anyone help me please

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7. (Original post by Misshussain23)

I'm not sure how you find x and y for part a 😬 can anyone help me please

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You can start with either one, so what do you know about one of the co-ordinates when the graph meets the x axis or the y axis?
8. (Original post by SeanFM)
You can start with either one, so what do you know about one of the co-ordinates when the graph meets the x axis or the y axis?
i'm not sure
9. (Original post by Misshussain23)
i'm not sure
We could work with a more simple example and apply the same logic to your question.

If you had the graph and sketched that, where does that cross the x and y axis? What do you notice about one of the co-ordinates in each case?
10. (Original post by SeanFM)
We could work with a more simple example and apply the same logic to your question.

If you had the graph and sketched that, where does that cross the x and y axis? What do you notice about one of the co-ordinates in each case?
One of them will be 0
11. y=f(x) so y=3x-x^3, when it crosses y axis, x=0 so sub in and get value of y

When it crosses x axis, y=0 so sub into eqaution and get value of y
12. (Original post by Misshussain23)
One of them will be 0
Correct, so now you just have to think: for meeting the x axis, which one will be 0? Same for the y axis, and then find the other co-ordinates.
13. (Original post by SeanFM)
Correct, so now you just have to think: for meeting the x axis, which one will be 0? Same for the y axis, and then find the other co-ordinates.
okay that makes sense thankyou
14. tou

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15. (Original post by Misshussain23)
tou

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Question 1 or 2?
16. (Original post by Andy98)
Question 1 or 2?
17. (Original post by Misshussain23)
My first step would be to rearrange the equation so you have y on one side. You know how to do that?
18. (Original post by Andy98)
My first step would be to rearrange the equation so you have y on one side. You know how to do that?
no im not sure, i know you have to find m by rearraringing it to y=mx+c but im not sure how to get it
19. (Original post by Misshussain23)
no im not sure, i know you have to find m by rearraringing it to y=mx+c but im not sure how to get it
What do you need to do to both sides to get a positive multiple of y?

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Updated: November 8, 2015
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