The price of a coat will be increased by 20% first and then reduced by 20%. Compared with the original price, the price of a coat will be increased by 20%

The price of a coat will be increased by 20% first and then reduced by 20%. Compared with the original price, the price of a coat will be increased by 20%

If the original price is 100, increase the price by 20% to 120 yuan
A further reduction of 20% is 96 yuan
So it's 96% of the original price, which is 4% less than the original price

123456789 + 123456789 times 100 is equal to?

24691357800

This is a square made of tangram. The side of the square is 20 cm long. What's the area of a parallelogram (as shown in the shadow) in the tangram?

20 × 20 × 18 = 400 × 18 = 50 (square centimeter); answer: the area of shadow is 50 square centimeter

If you multiply two-thirds, four seventh and eight ninth of a fraction by the same fraction, the product is an integer. What is the minimum fraction?
Don't forget to write down your ideas

The numerator should be the least common multiple of 3, 7 and 9, that is, the numerator should be 63;
The denominator should be the greatest common divisor of 2, 4 and 8, which is 2;
So this number is 63 / 2

359900358800 in scientific notation (three significant digits and four significant digits reserved)
If 359900 keeps three significant numbers and uses scientific counting method, it will become the 5th power of 3.60 * 10 (why, doesn't it mean to keep three digits accurate to the second place, and the third place's 9 will be rounded to 0, why the preceding 5 will be affected to become 6?) in this case, 358800 accurate to three digits is also the 5th power of 3.60 * 10, am I right
What happens if 359900 is represented by scientific notation and four significant numbers are retained?

No
358800 is accurate to three digits, not to the fifth power of 3.60 * 10
It's 3.59 * 10 to the fifth power
359900 = the fifth power of 3.599 * 10
Ask again if you have any questions

Unit 4 and unit 5 polysyllabic word formation

Unit 4: Chong, earn, sew, spray, rub, scatter, get, knot, hide, chirp, catch, fold, poor, plug, ride, animal, pen, park, cut, stuffy, place, finish, mix, shout, flourish, difficult
Unit 5: load, carry and paste
Sure, right!

If the line y = KX + B passes through point (1,3) and is parallel to y = - 3x + 5, find the function expression of y = KX + B

The line y = KX + B is parallel to y = - 3x + 5
k=-3
Because the line passes through the point (1,3)
3=-3*1+b
b=6
y=-3x+6

Junior high school mathematics problem: on the blackboard write 1, 2, 3 to 100, a total of 100 numbers, now arbitrarily erase two numbers, and then write the sum of the two numbers minus one
It's better to have only one number left. What's the number?

1+2+3+…… +100=（1+100）×100÷2=5050
Erase any two numbers, and then write the sum of the two numbers minus one,
There are 99 trees left, and their sum is 5050-1 = 5049
With each operation, a number is reduced on the blackboard, and the total is reduced by 1
When the last number is left, 99 numbers are reduced, that is to say, 99 operations are performed, and the total is reduced by 99
The sum is 5050-99 = 4951,
So the last remaining number is 4951

Concentrated sulfuric acid reacts with copper
What is the difference between strong acid and strong acid?

When concentrated sulfuric acid reacts with copper, it can be regarded as two steps: forming copper oxide, sulfur dioxide and water, and then sulfuric acid reacts with copper oxide to form copper sulfate and water. The first step is to oxidize copper into copper oxide, which is the performance of strong oxidation. The second step is to dissolve copper oxide to form copper sulfate, which is the performance of acidity
There is no absolute boundary between acid and strong acid, but strong acid can react with salt of weak acid to form weak acid. For example, sulfuric acid can react with sodium acetate to form acetic acid

It is known that point E is a point on the diagonal BD of square ABCD, EM ⊥ BC, en ⊥ CD, and the perpendicular feet are m and N respectively, connecting AE. Verification: Mn ⊥ AE

1. It can be proved by vector calculation that the sign of vector is slightly, EP through e is perpendicular to ad EQ, perpendicular to AB, and the perpendicular foot is p Q
MN=ME-NE
AE=AP+AQ
MN.AE= (ME-NE).(AP+AQ)=0
So Mn is perpendicular to Ae
2. It can be proved by congruence that ape is equal to men