Solving four mixed operation problems in Volume 2 of grade 4 of Jiangsu Education Press It must be more than 8

Solving four mixed operation problems in Volume 2 of grade 4 of Jiangsu Education Press It must be more than 8

1. Xiaofang spent two hours practicing calligraphy in the morning, 47 words per hour; and two hours in the afternoon, 53 words per hour. How many calligraphy did Xiaofang write in the whole day? (can you solve it in two ways?)
2. Umbrella 28 yuan watch 92 yuan
Aunt Wang bought four umbrellas and four watches. How much does it cost? Aunt Wang brought 500 yuan in total. Is that enough?
3. A cinema has 45 rows of seats. There were 28 seats in each row before. After the expansion, there were 22 more seats in each row. How many seats does the cinema have now?
4. There are 80 color TV sets in the store. After selling 25 sets, another 40 sets are shipped in. How many color TV sets do the store have?
5. A case of coke is 72 yuan, a case of 24 bottles, Xinxin wants to buy three bottles, how much do you need to pay?
6. The fruit shop brought 8 cases of apples and 8 cases of oranges. Each case of apples is 25kg, and each case of oranges is 20kg. How many kg of fruits did it bring?
7. Mr. Zhang wants to correct 58 compositions, and he has corrected 22. If he corrects 9 compositions every hour, how many hours can he finish it?
8. When participating in the spring tree planting, 52 people went to the fifth grade and each planted 26 trees; 48 people went to the fourth grade and each planted 25 trees. How many more trees did the fifth grade plant than the fourth grade?
I'm a fourth grade pupil. This is the problem in my exercise book. I hope you can choose me,

On the coordinate plane, there is an ellipse: x ^ 2 + 9y ^ 2-2x + 18y + 1 = 0 and a straight line: x-3y + 6 = 0. If the maximum distance from a point P on the ellipse to the straight line is a and the minimum distance is B, then
Why do a multiply B?

This is a problem of using the parameter equation of ellipse. If we simplify the equation: (x-1) ^ 2g9 + (y + 1) ^ 2 = 1, we get the parameter equation of ellipse as follows: x = 3cosa + 3Y = sina-1, then the coordinate of P is (3cosa + 3, sina-1). Using the distance formula from point to line: D = | 3cosa + 3-3sina + 3 + 6 | / √ (1 + 9) = | 3 √ 2Sin (a-45 °)

30 questions, similar to this 12.5 * 8.8
=12.8*（8+0.8）
=12.5*8+12.5*0.8
=100+10
=110

Methods: Methods: 16.9-5.6-4.49.08 - (5.7 + 1.08) 5.8 × 99 + 5.8 methods: Methods: 360 △ 1.2 △ 50 (40 + 1.25) × 8 483 + 199 1. Simple calculation

It is known that f (x) is an odd function defined on R. when x > equals 0, f (x) = x ^ - 2x, find the analytic formula

If x = 0, then f (- x) = (- x) ^ 2x
Since f (x) is an odd function on R, f (x) = - f (- x)
So f (x) = - f (- x) = - (- x) ^ 2x
When x > equals 0, f (x) = x ^ - 2x
When x

In special relativity, do two things happen at the same time and place in different reference frames at the same time?
Is the location the same?

If you see the same time, then the location must be different
And vice versa
The specific distance, time and distance can be calculated by Lorentz transformation formula

A rectangular sheet of iron, cut 8 cm from the long side, cut 4 cm from the short side, the square area is 116 square cm less than the original rectangular area, then the area of the original rectangular sheet of iron is how many square cm?

The length of the side of the square is a (8 + a) (8 + a) (8 + a) (4 + a) (8 + a) (8 + a) (4 + a) (4 + 4 + a (4 + a) (4 + a) - A2 = 116 & amp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp; & & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp; & & nbsp & nbsp & nbsp; & & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp; & & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp; & & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp & nbsp; & & nbsp; & & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; &A = 7 (8 + 7) × (4 + 7) = 15 × 11 = 165 (square centimeter) a: the area of the original rectangular sheet iron is 165 square centimeter

Given the sinusoidal AC voltage U = 311sin (314T + π / 6) V, calculate the maximum and effective value, angular frequency, frequency and period, phase and initial phase
Try to find: (1) maximum and effective value; (2) angular frequency, frequency and period; (3) phase and initial phase

The maximum value is 311, the effective value is equal to the maximum value / root 2, = 220; the angular frequency is 314, the frequency is 314 / 2pai, the period is 2pai / 314, the phase is 314pai + Pai / 6, and the phase is Pai / 6

You need at least () cm long wire to make a cuboid frame with a perimeter of 18 cm at the bottom and a height of 3 cm

At least (48) cm long wire is needed to make a cuboid frame with a perimeter of 18 cm at the bottom and a height of 3 cm
2 × 18 + 3 × 4 = 48 cm

Let's say that the power multiplied by the power arm is equal to the resistance multiplied by the resistance arm_________ Or________ , expressed as______ .

Balance principle of lever or horizontal condition of lever f1l1 = f2l2

The height of a cone is 10cm and the side view is semicircle. How many square centimeters is the side area of the cone?

Let the radius of semicircle be r and the radius of cone bottom be r
1/2*2π*R=2πr
H square + R square = R square
S = 1 / 2 * π r squared
So s = 200 / 3 * π