The tangent equation formula is: if the curve is y=f(x), the tangent equation at point (a, f(a)) is y=f'(a)(x-a)+f(a), and the normal equation formula is α*β=- 1.

The tangent equation of the function graph at a certain point (a, b) y = kx+b;

First, find the slope k, which is equal to the derivative value of the point function;

Then substitute the coordinate value of this point to find b;

Solving tangent equation;

regular expression

y=mx+c

m = 1/k； K is the tangent slope.

Then substitute tangent coordinates to get C.

Derivation rule of derivative of normal equation

The derivative function of a function composed of the sum, difference, product, quotient or mutual combination of basic functions can be derived from the derivative rule of the function. The basic deduction rules are as follows:

1, Linearity of Derivation: Finding the linear combination of derivative functions is equivalent to finding the derivatives of each part first and then finding the linear combination.

2. Derivative function of the product of two functions: one derivative times two+one derivative times two.

3. The derivative function of the quotient of two functions is also a fraction: (derivative times mother-derivative times mother) divided by mother square.

4. If there is a compound function, use the chain rule to deduce it.