Desperate math masters. Topics for the first year of junior high school.

Parse; 1.Solution: Let the waist length of the triangle be x and the bottom length be y.

If x+x 2=, x 2+y=, the resulting solution is 2x, so the lengths of each side of the triangle are 9cm, 9cm, and 7cm

2.Flipping the line segment is also translating the m-point.

Set m'The coordinates of the point are (x,y), x+2=3, y-3=4, x=1, y=7. i.e. m'The coordinates of are (1,1).

3.With respect to x-axis symmetry, the abscissa is unchanged and the ordinate is the opposite number, with respect to the y-axis symmetry, the ordinate is unchanged and the abscissa is the opposite number, and with the origin symmetry, the abscissa is the opposite number.

Therefore p1(-1,-2),p2(1,2),p3(1,-2)

4.Let the BC edge be the bottom edge, then the length of the bottom edge is 2 (1) 4, (the ordinate is the same), and the height is 1 (1) 2, (the absolute value of the abscissa difference).

So the area of the triangle is 4 2 2 4

5 This question seems to be wrong, I remember that the sum of the outer angles of each triangle is 180°, and the "sum" should be removed. In this way, one angle is 90°, and the difference between the two inner angles is 30°, one is 60° and the other is 30°.

6.The formula for the number of diagonal bars of a polygon is 0 5n(n 3), then 0 5n(n 3) 3n, n 9, the formula for the sum of the internal angles of a polygon is (n 2) 180°, (9 2) 180° 1260°

Answer: , 9cm, 7cm

3．p1(-1，-2），p2（1,2），p3（1,-2).

1.Waist = 9cm bottom edge = 7cm

2) p2(1,2) p3(1,-2)5.The outer angles of the triangle and can only be 360°! Edges).

1.The lengths of each side of an isosceles triangle are: 9cm, 9cm, 7cm

Now I realize that I have forgotten it, set of formulas.

Let this polygon variable be n

The sum of the inner angles of the polygon is 180 (n-2).

The sum of the outer angles is 180n-(180(n-2))=360--- this formula can be taken as an example of a triangle, each inner angle and the corresponding outer angle are complementary, and there are several angles then there are several 180 degrees, and then subtract the sum of the inner angles, so this formula can be obtained.

So according to the above two formulas, it can be obtained:

3x360-180（n-2）=180

Get: n=7

The sum of the outer angles of the convex polygon is 360 degrees, consisting of: inner 180=3 outside, so the sum of the inner angles is 900 degrees. The sum of the number of inside angles and the relation to the number of sides is: degrees and 180 (number of sides -2). So the answer is 7 sides.

According to the meaning of the question, 2ab-m = 1, when m=1, 3d 5m = 3d 5, c, d are the opposite numbers, 2ab-m -3c+3d 5m = 1-3c-3c 5=1-18c 5;

When m=-1, 2ab-m -3c+3d 5m=1-3c+3c 5=1-7c5

By |z+1|=2, you can get z=1 or z=-3, from xy 0, you can get x,y can not be positive or negative at the same time, from yz 0, you can know that y,z are either positive or negative at the same time, and then you can evaluate according to different situations.

Solution: The rent of each store in the first year is X million yuan, and the rent of the second year is (X + 6 thousand yuan

x x + solves this equation to get x=

It is verified that x= is the solution of the original equation.

X+ A: The rent of each store in the first year is 10,000 yuan, and the rent in the second year is 10,000 yuan (or the rent of each store in the first year is 5,000 yuan, and the rent in the second year is 6,000 yuan).

In the first year, there are y stores in x yuan, xy=60000(1000+x)y=72000

1000y=12000

y=12x=5000

$5,000 for the first year.

$6,000 for the second year.

If the rent of each store is x, you can get 60000 x=72000 (x+1000), and solve x=500

(1) The cost of each 10 books is: 15*10+6+2=158;2 is the remittance fee.

So x 10 = 790 158 = 50 times.

2) Total number: 10*5=50;Book price: 50*15=750;Postage: 750*10%=75;

Remittance fee: (750+75) 100=>9

Total cost: 750 + 75 + 9 = 834

2.The book price is 60*15=900;Postage: 900*10%=90 Obviously, the second type is expensive.

Then calculate the specific money.

Remittance fee: 990 10 = >10

Therefore, the total cost is: 900 + 90 + 10 = 1000

or 1, (10 15+6+2) x 10=790x=502, (50 15 (1+10%) 1+1%) = 834 yuan.

3. The first type (10 15 + 6 + 2) 6 = 948 The second type 60 15 (1 + 10%) 1 + 1%) 1000 Answer: The cost of 6 mail orders is less.

Let the two sides be A and B

then b=m-a

By the Pythagorean theorem.

a²+b²=1

a²+m²-2am+a²=1

2(am-a²)=m²-1

Area = ABA (m-a).

am-a²(m²-1)/2

Pick C However, this question is actually wrong.

Because 0 so m -1<0

This area is negative, so the title is incorrect.

Let the two adjacent sides be x and y respectively

So the square of x + the square of y = 1

x+y=m can be solved, xy=(m's squared -1) 2 choose c

x+y =m

x^2+y^2=1

so s=x*y=(m^2-1)2

c But your condition is wrong, the sum of the two sides of the triangle cannot be less than the third side.

You pirate, right? Have you ever seen a rectangle with a diagonal longer than two adjacent sides?

The length of the rectangle is a and the width is b

a+b=m --1a square + b square = 1 --21 square left and right.

a+b) square = m square.

Disassemble square A + square B + 2AB=M square --3 and substitute formula 2 into formula 3.

1+2ab=m-square.

ab=(m-square-1) 2

The answer is cps: the sum of adjacent edges m cannot be less than the length of the diagonal 1 The straight line between two points is the shortest, and the polyline must be greater than the length of the straight line.

The two adjacent edges are x and y

x+y=mx^2+y^2=1^2

Area = xy = 1 2 * 2 x y = 1 2 * [(x+y) 2-(x 2 + y 2)] = 1 2 * (m 2-1) choose c

3 negative, one positive, the result is negative.

Molecule = 1 4 9 18

Denominator = 2 3 4 5

Approximate denominator: the numerator denominator is about 4, the numerator 9 is about 3 = 3, and the numerator 18 is about 2 = 9, i.e.:

Numerator = 3 9 = 27 denominator = 5

First determine the positive and negative, then the numerator and denominator can be reduced to the fraction, and the direct multiplication that cannot be made, and finally -27 5

Is this a multiplication of four fractions?

Multiply one or four terms, multiply two or three terms = (9 5) (-3) = -27 5

First determine that it is a negative number, and then reduce it to -27 5

Solution: If there are x monkeys, there will be (3x+8) peanuts. According to the title:

3x+8)-5(x-1) 0 Total peanuts - Monkey with 5 peanuts 5 because there is one that doesn't score.

3x+8)-5(x-1) 5 to 5 pieces, so (x-5) monkeys are divided into 5 pieces, and the rest is not divided into 5, and the monkey with a solution set of 4 x 6 is divided into more than 0 and less than 5 is less than 5).

x is a positive integer.

x=5,63x+8=23,26 Answer: When there are 5 monkeys, there are 23 peanuts, and when there are 6 monkeys, there are 26 peanuts.

There are x monkeys, the second time to divide peanuts, the last monkey to get y 3x+8=5(x-1)+y

2x+y=13

Because y<5

So y=4,3,2,1

y=4, x= is not an integer, rounded.

When y=3, x=5 holds.

When y=2, x=is not an integer, rounded off.

When y=1, x=6 holds.

So there are 5 monkeys and 23 peanuts.

Or 6 monkeys and 26 peanuts.

Solution: If there are x monkeys, there are peanuts (3x+8).

From the meaning of the title, 3x+8-5(x-1)<5 13x+8-5(x-1)>0 2 The solution set of this group of inequalities is 4 because x should be a positive integer.

So x=5 or 6

When there were 5 monkeys, there were 23 peanuts, and when there were 6 monkeys, there were 26 peanuts.

Binary one-dimensional equation, Eq. 1, x 3-y=2 Eq. 2: x-y=4 can be calculated, but the result doesn't seem to be quite logical, hehe.

Let AOC be X, then BOC is 3X, so X+3X=180, so X=45 degrees.

And because the OC divides the AOD equally

So cod= aoc=x=45 degrees.

Let cod=x

Because the CD divides the ACD equally

So aoc= cod=x

Because AOC=1 3 BOC

So boc=3x

Because AOC+ COB=180

So x+3x=180

So x=45

So cod=45°