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## Homework Statement

If x1 is some value of x, u1is the corresponding value of u and y1 the corresponding value of y, then dy/dx at x = x1 is the product of dy/du at u1 and du/dx at x1.

This does not make sence....

example

IF: y = (x+2)^2

y=u^2 u = x+2

dy/du = 2u

du/dx = 1

I want to find the tangent at x = 2

The above statment says dy/dx = dy/du at point u1 time du/dx at point x1

dy/du @ x = 2 is 4

du/dx @ u =2 is 1

4*1 is 4 which is not the correct answer.....