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# c2 differentiation...again Watch

1. The normal to the curve y=ax^1/2 +bx at the point where x=1 has gradient 1 and intercepts the y axis at (0,-4). Find a and b.

Could someone tell me the steps to solve this and also any tips on how to solve these types of questions as I really struggle with figuring out the way to solve them.

Thanks
2. (Original post by hit94)
The normal to the curve y=ax^1/2 +bx at the point where x=1 has gradient 1 and intercepts the y axis at (0,-4). Find a and b.

Could someone tell me the steps to solve this and also any tips on how to solve these types of questions as I really struggle with figuring out the way to solve them.

Thanks
You should remember that a and b are just numbers, so treat them no differently and find the normal in the usual way (it will include a and b).

Then, note that, when a curve (or any function) intercepts the y axis, x=0.
3. (Original post by Indeterminate)
You should remember that a and b are just numbers, so treat them no differently and find the normal in the usual way (it will include a and b).

Then, note that, when a curve (or any function) intercepts the y axis, x=0.
I still don't get it. I've got y' as 1/2ax^-1/2+b =-1. How do I find the y coordinate and how does the normal include a and b?
4. (Original post by hit94)
I still don't get it. I've got y' as 1/2ax^-1/2+b =-1. How do I find the y coordinate and how does the normal include a and b?
From

notice that the gradient at x=1 will involve a and b (when you substitute in) so the gradient of the normal (negative reciprocal) will also involve a and b.
5. (Original post by TenOfThem)
This is not possible

Can you check the question
Why is this not possible?
6. Sorry stupid misread on my part
7. (Original post by notnek)
I think it is possible.

Spoiler:
Show
a=-4,b=1
Thats what I got

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