A few math questions Kneel down and ask for answers, ask for answers to these math questions

1.A and B have traveled for four hours in the whole process, and B has traveled a distance of 20-2=18 km, so his speed of B is 18 divided by 4 equals kilometers per hour, and the total distance traveled by A is 2 * (kilometers, so his speed is 184 divided by 4 equals 46 kilometers per hour.

2.It is not represented by a function containing the number x of students. If yes, it is solved like this: m=3x+8, m=5x-3 simultaneous equations are solved x=,m=.

3.Because eight is twice as many as four, and 36 is nine times as many as four, the number of four vehicles can be 1,3,5,7,9, and when the number of vehicles that can take 4 people is 1, the number of vehicles that can take 8 people is 4; When 3 cars are selected for 4 people, 3 cars are selected for 8 people; When you can take 4 people and choose 5 cars, you can choose 2 cars if you can take 8 people; When 7 cars can be selected for 4 people, 1 car will be selected for 8 people; When there are 9 cars for 4 people, 0 cars for 8 people can be selected.

When you can take 4 people to choose x cars, you can take 8 people to choose (36-4x) 8 cars, and the total amount of money used is 200x+(36-4x) 8*300, this function is the smallest, put 1,3,5,7,9 generations into it to see which small, small scheme is chosen.

1. Set the speed to v1 and v2.

v1+v2)*2=20

At the same time, the time for A to return in situ is also 2 hours, i.e. relative to B.

v2*4+2=20

Therefore, V2=V1=2, M books, n students won awards. Yes.

3n+8=m

0=5*(50-x), resulting in x<=20

520-4x>=14*(50-x), and x>=18 so there are three schemes, i.e., x

Set the total cost to y

Yes. y=,x takes the maximum value, then y reaches the minimum, that is, when x=20, y=84 yuan.

These few questions per minute, even calculation + input, took me half an hour, and I was exhausted.

yes, no points, no motivation, no points, forget it, there are still so many words, who will read it?

No points are really no motivation.

1.The original formula = 1-1 (x+1), and the range y is not equal to 1

2.odd function, y=x+a x=(x 2+a) x, when x>0, when x<0, write your own empty letter.

3.The crossing point (a,2a) means that it is either in the first quadrant or in the third quadrant, draw the diagram, the three sides are a, 2a, the root number 5a, when a > 0, sin a = two-fifths of the root number, cos a = one-fifth of the root number, tan a = 2, when the bucket wheel a<0, sin a = negative root number two-fifths, cos a = one-fifth of the root number, tan a = 2

y=x x+1 in the shirt annihilation range y≠1

y=f(x)=x+a parity of x.

f(-x)=-x-a x=-(x+a x)=-f(x), so y=x+a is an odd function.

sin = 2 yards of aura-5 5

cosα=±5/5

tanα=2

ad=cd

e and f are the midpoints of the cd and ad, respectively.

Closed erection ae=ce

ad=cdd=∠d

Sedan branch large CDF AED

ae=cf

Prove; In ADE and CDF, d= d

common corner) df=de

e, f are the midpoints of cd, ad, respectively).

ad=dc rhombic early line shape four sides of the land world are equal).

ade≌△cdf

Return to the type. ae=cf

Question 1:

A happens to catch up with B and does not collide, indicating that A's speed is exactly 5m s when A catches up with B, and if it exceeds it, it collides, and if it is lower, it is impossible to catch up.

Let the acceleration of the deceleration of the armor be a, then a=(15-5) 10=1m s 2

Let A and B be separated by l meters, A can see B, then there is the equation l+5*10=15*, and the solution is l=50m

When 20m apart, there is an equation: 50+5*t-(15* solution to t=10+2*root number 10 and 10-2*root number 10

The first solution is 10+2*the root number 10 is rounded, so t=

Question 2 1If the length is 100+x, then the width is (600-2*(100+x)) 2=(200-x).

So (100+x)*(200-x)=20000, the solution is x=100

2.(100+x)*(200-x)=23000, b 2-4ac<0, no solution.

Question 3 x+y=68+2

x*y=300

The solution is x=20 and y=15

The fourth problem x 2+x+a=x 2+ax+1 has a common root x=1

Substituting any equation yields a=-2

It took a long time to adopt it

What grade math problem is this?

Time is limited.

1 2 questions are too lazy to do (in fact, they can't do it).

3：x+y+2=70

x+2)*y=300

If this equation doesn't come out of the result.

Just: x+y+2=70

x*（y+2）=300

4:x2+x+a=0

x2+ax+1=0

x+a=ax+1

x-ax=1-a

x(1-a)=1-a

so:x=1 a=-2

If you do it in a hurry, if you make a mistake.

Don't spew my saliva.