Derivative is a tool, which is mainly used to study the monotonicity, extreme value and maximum value of functions. The relationship between derivative and monotonicity can be understood mainly from the combination of numbers and shapes and the idea of replacing curves with straight lines. The image of the function is infinitely close to the tangent of this point, and the curve can be replaced by the tangent of this point, so the derivative is the slope of the tangent, so the derivative is greater than 0, and the tangent of this point Y increases with the increase of X, so the curve of this point also increases with the increase of Y. With monotonicity, it is easy to understand the extreme value and the maximum value in combination with the image. So the derivative problem in high school will not be difficult. Just remember the following points.
1, the derivative formula is memorized, and the derivative operation is also familiar (at present, the formula itself is unreasonable and can only be memorized).
2, f' (X.) stands for tangent slope 2, f '(x X, y.),
3, f ′ (x) > 0-monotonically increasing (think of the right when you see the left, and the left when you see the right),
4，f '(x)& lt； 0- monotonically decreasing (think of the right when you see the left, and the left when you see the right).