Normal equation: y-f (x0) =-1/f' (x0) * [x-x0]

Because the tangent point on y = x 2 is (1, 1).

So y-1=-1/2 (x-1).

Finishing, y=- 1/2x+3/2.

Conclusions used:

1, tangent multiplied by normal =- 1

2. There is a corresponding relationship between tangent slope and derivative.

Extended data:

Derivation rules of derivatives:

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.

Baidu Encyclopedia-Normal Equation