Yeah but what if in the exam I think about using the equation, then I'll have two different answers so I must know why we can't use the equation
What's stopping you?
Use that only if you have the points and gradient but not the equation. For example finding tangent to the line or the normal equation. Here they give you the derivative of the curve. So just integrate find C by subbing the points and that's your equation; y=2x^3-6x-5
No you are right, you can not use
Is this correct, btw how do I make it show the image in the thread?It's so much easier with the 3U method, wish we could use it
For this question why can't we use?)
When you have the gradient of the entire function, not just a tangent.No you are right, you can not use
Think about what this equation actually means. i.e. when can you use it?
He's asking why does it give you a different answer, not necessarily which method is better.
That is true. But on a more general level, what does using that equation imply about the curve that may not be true? (in this case it isn't true, which is why you can't use it).
Because the gradient isn't 6 it's 2.. Plus you can use that way.. Just with the gradient of 2 not 6
It gives a different answer because the derivative of the equation only gives you the gradient at a point, if you try to put that gradient into the equation: y-y1=m(x-x1) then you will find the equation of the tangent to the curve at that point.
If you are referring to using
Pretty much. A better explanation would be that using
You can only usePretty much. A better explanation would be that usingimplies that the curve is a straight line. But this isn't always the case, which is why you can't always use it.
Yes trueYou can only use
uv'+u'vFind the derivative of: