# Math question c2 differentiation

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#1
I don't understand the question where you have a equation and your expected to find the coordinates or the stationary point out of nothing? Like for example 3 root x - 5x +1, I can differentiate this but I csnt find the coordinates how do I do it? I can't solve it
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5 years ago
#2
(Original post by SunDun111)
I don't understand the question where you have a equation and your expected to find the coordinates or the stationary point out of nothing? Like for example 3 root x - 5x +1, I can differentiate this but I csnt find the coordinates how do I do it? I can't solve it
Stationary points are where dy/DX is 0

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5 years ago
#3
At stationary points, dy/dx = 0. From there, you rearrange the differential to get the x-coordinate of the stationary point. You sub this value back into the original equation to find the y coordinate of the stationary point.
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#4
(Original post by aoxa)
At stationary points, dy/dx = 0. From there, you rearrange the differential to get the x-coordinate of the stationary point. You sub this value back into the original equation to find the y coordinate of the stationary point.
That's just it I can do dy/dx but I can't solve it when it's equal to 0, I don't understand how..
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5 years ago
#5
(Original post by SunDun111)
That's just it I can do dy/dx but I can't solve it when it's equal to 0, I don't understand how..
What was the original equation of the curve, and what did you get when you differentiated it?
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#6
(Original post by aoxa)
What was the original equation of the curve, and what did you get when you differentiated it?
When I dy\dx it is 3/2x minus to power of 1/2 - 5 = 0 I just can't work out coordinate
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5 years ago
#7
(Original post by SunDun111)
When I dy\dx it is 3/2x minus to power of 1/2 - 5 = 0 I just can't work out coordinate
Rearrange for x and then substitute your x value into the original equation.
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5 years ago
#8
(Original post by SunDun111)
When I dy\dx it is 3/2x minus to power of 1/2 - 5 = 0 I just can't work out coordinate
I presume you can rearrange it to x^(-1/2) = 10/3 - this is just adding the 5 across, multiplying by 2, then diving by 3 so you get the x term on it's own.

As you have the x term to the power of (negative) a half, this is the square root. To get rid of a square root, you square both sides to get x^-1 = 100/9

Can you rearrange that to get what x equals?
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