Find the maximum value of the function y = x ^ 2 + 2aX in the interval [- 1.1]

Find the maximum value of the function y = x ^ 2 + 2aX in the interval [- 1.1]

Find out that the derivative of Y is 2x + 2a, make the derivative equal to 0, get x = - A, discuss a, and then calculate it in no interval, the biggest one is

If the function y = ax & # 178; - 2aX (a ≠ 0) has the maximum value in the interval [0,3], find the value of A
If the function y = ax & # 178; - 2aX (a ≠ 0) has the maximum value 3 in the interval [0,3], find the value of A

A is negative, is it wrong?

When x ∈ [0,2], the function f (x) = ax & # 178; + 4 (A-1) x-3 obtains the maximum value when x = 2, then the value range of a is
I am very poor in mathematics. There are three situations in the answer, the other two are not consistent with the meaning of the question. The second situation is that if a > 0, then - 4 (A-1) / 2A ≤ 1, the solution is a ≥ 2 / 3. What I want to ask is, how does - 4 (A-1) / 2A ≤ 1 come from, and I can't think about it. And after reading this question, Baidu knows that there are many different answers

When the coefficient of quadratic term is unknown
We should discuss the quadratic coefficient first
If a = 0
Original formula = - 4x-3
Take the maximum value at 0
Not in line with
When a