Differentiate y= (2x+1)^3. [The chain rule]

For maths questions I feel that getting your head around the concepts are difficult but once achieved allow you to comfortably answer a wide range of questions. Therefore for maths tuition I think it is important to find a method that works for the student and then practice using it through multiple questions.  

Obviously it is easier to discuss concepts face-to-face however for this example I've found a four step process helps me answer questions on the chain rule. 

1) Differentiate the thing in the brackets

 y = 2x+1    -->      dy/dx = 2

2) Multiply that by the induction outside the bracket

2 X 3 = 6

3) Stick this number before the initial bracket

6(2x+1)^3

4) Minus 1 off the initial indicy

6(2x+1)^2 

So dy/dx = 6(2x+1)^2

This is just one method. There is another one substituting U into the equation and then saying [du/dx X dy/du = dy/dx]. I would go through both methods with the students so they can use the one that works for them. 

JJ
Answered by James J. Maths tutor

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