Some of the first year math problems are urgent

a c b Above is the diagram of the first question.

Because ac+bc=ab, ac=1 2ab;

So bc=1 2ab;

And because bc=12cm

So ab=2bc=24cm;

a c d b

Above is the diagram of the second question.

Because da=6, db=4

So ab=da+db=10

And because ac=cb=1 2ab

So cb=1 2ab=5

So cd=cb-db=1

The third question corrects you a little, n should make the midpoint of bc correct. Here is the figure:

a m c n b

Because AC+CB=AB

and because am=mc=1 2ac; cm=mb=1 2cb, so mn=1 2ac+1 2cb=1 2(ac+ab)=1 2aba e b c f d

Above is the diagram of the fourth question.

Because AD=AB+BC+CD=14cm;

And because ab:bc:cd=2:3:2

Therefore, ab=4cmbc=6cmc=4cm, and because e, f, are the midpoints of ab and cd, respectively, eb=ae=2cm, cf=fd=2cm

So EF=EB+BC+CF=2cm+6cm+2cm=10cma p m n q b

Above is the diagram of question 5.

Because ap=pm=1 2am,nq=qb=1 2nb;

So 2pq=2(pm+mn+nq)=2pm+2mn+2nq=am+2mn+nb=(am+mn+nb)+nn=ab+mn

So 2PQ = AB+MN

If (a b + b a) + 2 = ab

Then a+b=ab.

Solution: obtained from a b + b a) + 2 = ab.

a*a+b*b+2ab)/ab=ab

i.e. (a+b) 2=(ab) 2

So a+b=ab

Solution (1) if: b a+a b = ab-2

Then a+b=ab.

2) Because, b a+a b = ab-2

Then: b + a ab = ab-2

b²+a²=a²b²-2ab

a+b)²=a²b²

Because, a 0, b 0

then, a+b=ab+

Personally, I think there are already answers!

Solution: If you can use x feet of cloth to make tops, and you can use y feet of cloth to make sleeves, the number of tops is x 8, and the number of sleeves is y 2

According to the meaning of the title, if it is just matched, that is, the number of sleeves is twice the number of tops: 2*x 8=y 2

Get x y=2, i.e. divide the cloth into 3 equal parts, 2 parts for the blouse and 1 part for the sleeve tube.

The cloth for making the jacket is: 300*2 3=200, and the cloth for the sleeve tube is: 300-200=100

The number of tops that can be made: 200 8=25

A piece of clothing is 1 top top body + 2 sleeves, if a total of x pieces of clothing is made, then (8 + 2 * 2) * x = 300, x = 25 pieces of clothing.

It should be 25 * 8 = 200 feet of cloth for the body, and 25 * 4 = 100 feet of cloth for the sleeve tube.

You don't have a total number of how to do this topic, wow.

Dizzy, the topic is not complete, so you can do anything.

The ruler cloth is used for the body, and the 60-foot cloth is used for the sleeve tube.

2.300 (8+2)=30 (pieces).

1. Use a square with a side length of 10cm to enclose the side of a cylinder (unsealed and omitted), and ball the volume of the cylinder (use pai four tones here).

10 (2) is the radius of the bottom surface *10 (2))2*10=250

2. The side view of the cylinder is a semicircle, and the ratio of its side area to the ground area is found.

The side view of the cylinder is rectangular, and this question can't be done.

3. A rectangular tabletop, rejecting one corner, and how many corners?

4. A cube with a side length of 1cm, there is a spider lurking in the lower left corner of the front, and there is a moth in the upper right corner of the back.

1 + root number 2

1, s=pai*r squared circumference c=2*pai*r v=s*h=(c 2*pai) squared *pai*h=100*pai*10 4=

2, the second question should be a cone, c=2*pai*r base area s=pai*r square c1=c=pai*r

s=pai*r squared 2 r=r 2s s=8

3, 5 feet.

4, root number 5... The reason is to put the cube, the shortest straight line between two points.

Actually give 0 points?!! Uncle, why are you so picky?

(1) Since it is a sixth, then (2-m) cannot be equal to 0, and n=2, i.e., m≠2, n=2

2) Since it is a sixth polynomial, then the nth power y of (m+5)x will not be equal to 0, that is, the coefficient (m+5)≠0, m≠-5 n=6-1=5 (because the exponent of y is 1).

2. 9 people aged M, the total number is 9m; 24 people aged n, the total is 24n; There are also 40-9-24 = 7 people who are S years old, and the total number is 7s; Add the three and divide by 40 to get the average age.

9m+24n+7s）÷40;

If m 7, n 8, s 9, the average age of the class is years.

: Simplify, then evaluate.

2x-y) -2x+y)(2x-y)-2y, where x=1 2, y= -2

4x²-4xy+y²-4x²+y²-2y²=-4xy

4: Knowing x +2xy+y = 0, find the value of the algebraic formula x(x+4y)-(x+2y)(x-2y).

i.e. (x+y) = 0

So x+y=0

Original = x +4xy-(x -4y).

x²+4xy-x²+4y²

4xy+4y²

4y(x+y)

4y*00: At present, the research and development of nanotechnology has been widely valued by countries around the world, China's research in this field is at the world's leading level, nanometer (mm) is a unit of length, 1 meter = 10 9 nanometers, try to calculate the volume of a cuboid with a length of 5 meters, a width of 4 meters, and a height of 3 meters. (The final result is expressed by scientific notation).

5 10 9 nm long.

Width 4 10 9 nm.

High 3 10 9 nm.

So the volume is 5 4 3 (10 9) 3

6 10 28 cubic meters nanometer.

(1)(2x-y)²-2x+y)(2x-y)-2y²=(2x-y)²-4x²-y²)-2y²

4x²-4xy+y²)-4x²+y²-2y²=-4xy

When x=1 2 y=-2, the original = 4

2) x(x+4y)-(x+2y)(x-2y)=x²+4xy-(x²-4y²)

4xy+4y²

4xy(x+y)

x +2xy+y =0 (x+y) =0 original = 0 (3) v = 5x4x3 = 60 cubic meters.

60x10 27 cubic nanometers.

Cubic nanometers.

(1) (2x-y) -2x+y)(2x-y)-2y =(2x-y)(2x-y-2x-y)-2y =(2x-y)(-2y)-2y=-2y(2x)=-4xy When x=1 2,y= -2, the original formula=-4*1 2*(-2)=4

2) x +2xy+y =0 so (x+y) =0 x+y=0 x(x+4y)-(x+2y)(x-2y)=4xy+4y=4y*(x+y)=4y*0=0

3) 27th power of 5*4*3*10 = 27th power of 60*10.

1. The area of the square is a square meter.

The area of a flower bed is b

So the lawn area is a -4b square meter.

2. So a +5ab + 4b = (a + b) (a + 4b).

Solution: s=a -4b

Substituting a = 84, b = 8 to get :

s=6800

Total need: 6800 5 = 34000 (yuan).

Answer: The lawn area is (A -4B)m, and a total of 34,000 yuan is required.

Solution: The length of the rectangle is (a+4b) and the width is (a+b).

According to the figure, it can be obtained:

Original = (a+4b)(a+b).