What is the minimum value of the function y = - x ^ 2 + 4x - 2 in the interval [1,4], and draw its image

What is the minimum value of the function y = - x ^ 2 + 4x - 2 in the interval [1,4], and draw its image

y=-x^2+4x-2
=-(x^2-4x)-2
=-(x-2)^2+2
∵ axis of symmetry x = 2 ∈ [1,4]
When x = 4, the minimum value of Y is: Ymin = - (4-2) ^ 2 + 2 = - 2
Image: opening downward, axis of symmetry x = 2, vertex a (2,2), B (2 - √ 2,0), C (2 + √ 2,0), respectively smooth connection AB, AC and downward extension, the resulting image is the function

For a project, team a needs 40 days to complete it alone. If team B does it 30 days first, team a and team B work together for 20 days to complete the task. How many days does it take team B to complete the task alone?

It takes m days for team B to complete the task alone. According to the meaning of the question, it is 140 × 20 + 1m × (30 + 20) = 1. The solution is m = 100. It is tested that M = 100 is the solution of the original equation. Answer: it takes 100 days for team B to complete the task alone

A has 25 yuan, which is 20% of the total number of a and B. how much does B have?
Party A has 400 yuan and Party B has 150 yuan. If Party B gives part of the money to Party A, then Party B's money is 10% of Party A's money. How much money should Party B give to Party A?

Suppose B has x yuan
∴20%(x+25)=25
Suppose B should give X Yuan to a
∴150-x=10%(400+x)