Regarding the two application problems of college mathematics, I am about to make up the exam, and I

1.Set an average of x meters per day.

5*300+20*x=8500 repaired + repaired in the next 20 days = total length x=350

2.Area = 280 * 250 = 70,000 square meters = 7 hectares of carob area 7 = 40% carob = hectares.

Cucumber = ha.

(1) Solution: Set the remaining average daily repair x meters.

8500-20x=300

20x=8500-300

x=8200/20

x=410 A: The average daily repair is 410 meters.

2) The first question: 280 * 250 = 70,000 square meters = 7 hectares The second question: cucumber 7 * 60% = hectares of carob hectares.

A: 7 hectares. The area of cucumbers is hectares, and the area of beans is hectares.

1. Set an average of a meter per day.

Solution: 300 5+20a=8500

250 = 70,000 square meters = 7 hectares of cucumbers: 7 60% = hectares.

Carob: 7 40% = hectares.

1. Equations.

Set to repair x meters per day.

20x+5*300=8500

x = 350 * 250 = 70,000 square meters = 7 hectares 7 * 60 = hectares.

The first question is even odd zero, and the second question is set to t for the root number. La-la-la.

Hello answer, I'm glad to help you, can I talk about a specific math problem, I'm good to answer for you as soon as possible, please describe the problem specifically, I will answer the question for you in detail.

Okay, please wait a minute, I'm working hard to answer for you, this is the analysis of this question, may I ask if there is anything else I can help you Question 1 (2).

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Find the partial derivatives for x and y respectively, and make them 0, and obtain.

20x-8y+32=0,-4y-8x+14=0 to obtain the unique solution x=1,y=3 2

So this is the only extreme point, then x=1, y=time trouble, r is maximum r(1, profit function r(x,y)=xp1+yp2-c(x,y), bring in p1=200-20x, p2=120-5y, get.

r(x,y)=160x-20x +80y-5y-30 as above, so that the deviation vertical bend is 0, obtained.

160-40x=0,80y-10y=0, x=4,y=8x=4,y=8, when the manufacturer's profit margin is maximum r(4,4).

The topic is simple. Question 20, the derivative of tan(x) is the square of sec(x), so an=1 (n+1), so the conclusion is very obvious. Question 21, an+a(n+2) is equal to an of question 20, so bn=1 (n*(n+1))=1 n-1 (n+1), consider the sum of n terms of bn sn=1-1 (n+1), so that n tends to infinity, that is, the conclusion.

, 120 4500 95% = 513000 (yuan) 513000 1% = 5130 (yuan).

5130 = 513000 = 518130 (yuan) Answer: A total of 518130 yuan.

A combination of front gear 24 and rear gear 36 should be chosen.

Because: the front gear is the driving wheel, pedal with the foot, the rear gear is the driven wheel, drive the wheel to rotate, the smaller the front gear, the faster the speed, but the power is large. The larger the rear gear, the faster the speed, but also the more power it needs.

Let g(x) = f(x)-x, we know that g(x) is differentiable on [0,1], g'(x)=f'(x)-1,g(1)=f(1)-1, so g(1) is less than or equal to 0, g(0)=f(0), so g(0) belongs to [0,1], can g(0)*g(1)<=0 so g(x)=0 must have a root on [0,1], and because g'(x)=f'(x)-1 is not equal to 0, so g(x) has monotonicity on [0,1].

In summary, g(x)=0, and there is only one on [0,1], that is, f(x)=x is satisfied