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X÷9=90 to solve the equation?

Reference answer:

Fill in the blanks.

1. There are 40 books in the corner of the classroom, and I bought an A book. Now I have (40+a) books.

2.50 1 class has students a, including boys b and girls (a-b).

3. Master Wang produces X parts per hour, 10 hour (10x).

4. I bought 400 kg of rice in the canteen and ate 1 kg every day. After eating for a few days, there are only 2 kilograms left, which has been eaten for ((400-b)÷a) days.

Miao Yin is one year old, her mother is more than five times that of Miao Yin, and her mother is (5a+3) years old.

6. The number A is X, which is smaller than the number B by Y. The sum of the two numbers A and B is (2x+y), and the difference between the two numbers is (y).

7、? A coat 45 yuan, a pair of pants 43 yuan. What do you need to buy B sets of such clothes (88b)? Yuan.

Fill in the blanks according to the algorithm.

1、 15+a=(a)+( 15)？ a×36=(36)×(a)

2、m×4×0.25=(m)×[(4)×(0.25)]

3 、( a+b)×c=(a)×(c)+(b)×(c)

4、m-a-b =(m)-(a)+(b)]

Third, omit the multiplication sign and write as follows.

n× 12=？ 12n y×y=y a×b=？ ab X×8×Y= 8XY

(a+b) × b = (a+b) b (or ab+b? ) ? 2×c+6= 2c+6？ 7×n-5×n=2n2×a×b=？ 2ab

Fourth, find the following values.

1，A = 2.5，B = 1.5。 What is the value of 4a+2b? .

4a+2b = 4×2.5+2× 1.5 = 13

2, known x = 0.5, y = 2? Find the value of 5y-xy.

5×2-0.5×2=9

3. Given m = 3 and n = 4, find the value of11m+11n.

1 1×3+ 1 1×4=77

Fifth, solve the problem.

1, the bookstore bought two new boxes of pencil boxes. The first box has A and the second box has B. As a result, the first box sold m yuan more than the second box.

(1) The price of each pencil box is expressed by a formula. m \u( a-b)

(2) When A = 30, B = 25 and M = 60, what is the price of each pencil box?

60÷(30-25)= 12 (yuan)

A: The price of each pencil box is 12 yuan.

2. As shown in the figure, the side length of the big square is a cm, and the side length of the small square is b cm.

(1) The area of the shaded part is expressed by the formula.

Answer? -B?

(2) When a= 12 and b=3, what is the shadow area?

12? -3? = 135 (square centimeter)

A: The shadow area is 135 cm2.

Reference answer:

Fill in the blanks.

1. In order to celebrate the anniversary, a real estate in our city benefited the people and decided to reduce the price of the commercial house with the original price of A yuan/square meter by 10%, and the sales price after the price reduction was (a( 1- 10%)).

2. The price of greeting cards is 5 yuan per card. On Teacher's Day, Miao Yin bought C cards for her teacher with her pocket money, so Miao Yin spent (5c) yuan.

3. What is the length of the rectangle? 8m, what is the width? Am, what is the circumference of the rectangle? 2(8+a)？ ) centimeters.

4. It takes M yuan to buy a badminton racket, N yuan to buy a table tennis board, and (5m+8n) yuan to buy five badminton rackets and eight table tennis boards.

5. Xiao Li planted a tree seedling with a height of 1.8m, which will grow by 0.3m every year, so the height of the tree after t years is (1.8+0.3t) m..

Second, the judgment question. (Mark "√" for the correct picture and "×" for the incorrect picture)

1. When x=5, 2x2+3=43. (×)

2.A minus B, the difference is B, A is X, and B is X+B. (×)

My mother is X years old and Miao Yin is Y years old. 10 years later, my mother is (x-y) years older than Mingming. (? On the first day of London Olympic Games, China won m gold medals in the morning, n gold medals in the afternoon, and * * * won (m×n) gold medals on the same day. (×)

Third, list formulas that contain letters.

1, 6.8 times less than x's 12 times. 12x-6.8

2.a multiplied by a number 5 greater than B ...? a(b+5)

3. The sum of 3.3 times of A and 4.2 times of B? 3a+4.2b

4.x minus 0.3 is 4.5 times 4.5(x-0.3) of the difference.

5. Six times the sum of half of A and B (+b)

Fourth, solve the problem.

1. The total number of seats in the cinema is row m. If the number of seats in the first row is A, and the number of seats in the last row is always more than that in the previous row 1, how many seats are there in row M of the cinema?

According to the meaning of the question, the first row has seats, the second row has (A+ 1) seats, … and so on, row m has (A+M- 1) seats.

Teacher Chen went to the sporting goods store to buy badminton rackets for the school. The unit price of each badminton racket is one yuan. You can get a 30% discount if you buy badminton rackets above/kloc-0, which is expressed by the formula with letters:

(1)30a×0.7=2 1a (yuan)

Answer: You should pay RMB 2 1a for purchasing 30 badminton rackets.

(2) from the meaning of the question.

① when 0 < b ≤ 10 is an integer, buy b badminton rackets and pay ab yuan;

② when B > 10 is an integer, you need to pay 0.7ab yuan to buy a badminton racket.

Reference answer:

1. Fill in the serial number of the following formula in the corresponding position as required.

①? 5+7= 12? ②? 5+5x=40 ③？ 18-6x ④？ x+5=8

⑤? 9.2+3x= 15.2⑥？ x- 18 & lt； 34⑦? 0.5x=2⑧？ 4.4+x & gt； 15.7

Equation: ① ② ④ ⑤ ⑦

Equation: ② ④ ⑤ ⑦

Second, judge whether the following statement is correct.

1, equations are all equations, but equations are not necessarily equations. (√)

2. Formulas containing unknowns are called equations. ? (×)

3, 16=4x-8 is not an equation. (×)

4.9.3- 1.3= 10-2 is an equation. ( √)

5、6x-5 & lt； 23 contains unknowns, so it is an equation. (×)

If a=b, fill in the blanks according to the nature of the equation.

a+3=b+(3 ) a-(c)=b-c

a×d = b×(d)a \u( 10)= b \u 10

Fourthly, the following quantitative relations are expressed by equations.

1, the puppy weighs akg, the kitten weighs 3kg, and the puppy weighs 3kg more than the kitten.

Equation: a-3=3

2. Miao Yin's family used 7.5 tons of water last month, at the price of X yuan per ton, and one * * * will be paid to 30 yuan.

Equation: 7.5x=30

Fifth, solve the problem.

Grandma Wang wants to pickle pickles with a bag of 300 Jin of salt. She wants to divide the salt into three equal parts, but she only has 5g and 30g in her hand. How many times does grandma Wang have to weigh herself? How do you call it?

Grandma Wang has to weigh this balance at least three times.

1: Weigh out 35g of salt with 1 5g and 1 30g weights.

Second time: weigh out 1 30g of salt 65g, salt 35g, and the combination of salt 65g and salt 35g is salt 100g.

Third time: weigh out 100g salt with 100g salt, leaving 100g salt.

Reference answer:

Solving equations in the first volume of the fifth grade (1)

1, solve the equation.

x+ 140=290

Solution: x+140-140 = 290-140.

x= 150

x÷2.5= 100

Solution: x÷2.5×2.5= 100×2.5.

x=250

x-87=275

Solution: X-87+87 = 275+87

x=362

77-x=2 1.9

Solution: 77-x+x = 2 1.9+x

77=2 1.9+x

77-2 1.9 = 2 1.9+x-2 1.9

x=55. 1

77÷x= 1 1

Solution: 77 ÷ x × x =11× x.

77÷ 1 1 = 1 1×x÷ 1 1

x=7

6.2x= 124

Solution: 6.2x÷6.2= 124÷6.2

x=20

39÷x=3

Solution: 39÷x×x=3×x

39÷3=3×x÷3

x= 13

4.4x=44

Solution: 4.4 times ÷4.4=44÷4.4

x= 10

2. Modify the following formula.

( 1) X-5.6= 16.2

Solution: x-5.6+5.6 =16.2+16.2.

X = 32.4

Correction: X-5.6= 16.2

Solution: x-5.6+5.6= 16.2+5.6.

x=2 1.8

(2) 10x=5

Solution: 10x÷ 10=5÷5

x= 1

Correction: 10x=5

Solution:1x ÷10 = 5 ÷10.

x=0.5

(3)x- 1.5=3.6

Solution: x-1.5+1.5 = 3.6-1.5.

x=2. 1

Revision: x- 1.5=3.6

Solution: x-1.5+1.5 = 3.6+1.5.

X =5. 1

3. Use the equation to express the following equivalence relation and find the solution of the equation.

Four times (1)x equals 22.

x×4=22

Solution: x×4÷4 =22÷4

x=5.5

(2) The difference between X and 6.6 is 12.4.

x-6.6= 12.4

Solution: x-6.6+6.6= 12.4+6.6.

x= 19

(3) x divided by 4.8=5

x÷4.8=5

Solution: x÷4.8×4.8=5×4.8.

x =24

4. Solve application problems according to the problem meaning equation.

(1) To build a runway, 400 meters have been built, with 800 meters left. What is the total length of this runway?

Solution: Let this runway be x meters long.

x-400=800

x-400+400=800+400

x= 1200

The total length of this runway is1200m.

(2) Grade five students plant trees, with 56 trees in one class, twice as many as Class Two. How many trees have Class Two planted?

Solution: Set up two classes to plant X trees.

2x=56

2x \2 = 56 \2

x=28

Answer: Class Two planted 28 trees.

Reference answer:

1, solve the equation.

2x- 16=5.6

2x- 16+ 16 = 5.6+ 16

2x=2 1.6

X= 10.8

3.2x+ 1.5×2= 12.6

3.2x+3= 12.6

3.2x+3-3= 12.6-3

3.2x=9.6

3.2x÷3.2=9.6÷3.2

x=3

5(x-2.5) =5.5

5(x-2.5)÷5 =5.5÷5

x-2.5= 1. 1

x-2.5+2.5= 1. 1+2.5

X=3.6

3.6(5 times) =7.2

3.6(5-x)÷3.6 =7.2 ÷3.6

5 x = 2

5-x+x =2+x

5=2+x

5-2=2+x-2

X=3

(x+6.9)÷4=2.5

(x+6.9)÷4×4=2.5×4

x+6.9= 10

x+6.9-6.9= 10-6.9

x=3. 1

(2x-4.6)÷6= 1.8

(2x-4.6)÷6×6= 1.8×6

2x-4.6 = 10.8

2x-4.6+4.6 = 10.8+4.6

2x = 10.8+4.6

2x= 15.4

2x \2 = 15.4 \2

x=7.7

2. Fill in ">" in ○. "<" or "=".

(1) when X=2.5, 10x-3 < 28? 10X+3=28

(2) When X=4, 6.2+x

(3) when X=5, 9x+X >；; 45 9X-X & lt； 45

(4) when X=5, (5x+3) ÷ 5 >; 5(5x-3)5 & lt； five

3. Column equations and solve them.

3.3 times of (1)x minus the product of 1.2 and 4, the difference is 1 1.4.

(2) The sum of x and 3.4 divided by 6 equals 1.5.

(3) Four times x minus 1.6 equals 7.2.

4. Solve application problems according to the problem meaning equation.

(1) Grade 4 * * *, with 200 students. During extracurricular activities, 80 girls went to jump rope. The boys are divided into five groups to play football. How many people are in each group?

Suppose there are x people in each group on average.

80+5x=200

80+5x-80=200-80

5x=200

5×5 = 200×5

x=24

Answer: There are 24 people in each group on average.

(2) Li Shifu bought 72 meters of cloth just to make 20 clothes for adults and 16 clothes for children. Adult dresses are 2.4 meters each, and how many meters are children's dresses?

Cover each child's clothes with x meters of cloth.

2.4×20+ 16x=72

48+ 16x=72

48+ 16x-48=72-48

16x=24

16x÷ 16=24÷ 16

x= 1.5

A: The fabric of each children's wear is1.5m. 。

5. Fill in the appropriate numbers in () so that the solution of each equation is x=8.

(x-3)×( 1. 1)=5.5

(3.5 )÷( 15-x)=0.5

5x+3×(2.9)=48.7

(5x+ 12)÷(2)=26

Reference answer:

First, solve the equation and test.

x= 12 x=7 x=2

x = 2 x = 1 1 x = 14.3

Second,

1, 3x+ 12=842, 40×9+9x=8 10 or 9×(40+x)=8 10.

Third,

1, solution: Let the area of Tiananmen Square be x million square meters.

2x- 15=73

x=44

The area of Tiananmen Square is 440,000 square meters.

2.( 1) solution: suppose that the elephant can reach x kilometers per hour at the earliest.

2x+30= 1 10

x=40

A: Elephants can reach 40 kilometers per hour at the fastest.

(2) Solution: Let the car run at the speed of X kilometers per hour.

2x-20= 1 10

x=65

The car travels 65 kilometers per hour.

3. Solution: This piano has X black keys.

1.5x-2=52

x=36

This piano has 36 black keys.

4. Solution: X peaches were shipped.

x+3x=360

x = 90°

90×3=270 (piece)

There are 270 apples and 90 peaches.

Reference answer:

I x= 1.4 x=3 x=2

x=0.4 x=4 x=8

Second,

1、9x-4x= 180 x=36

2、8x- 14=58 x=9

3、0.75x=2.4×6 x= 19.2

Third,

1, solution: let the price of each pencil be x yuan.

( 1.5+x)×6= 13.8

x=3.2

The price of each pencil is 3.2 yuan.

2. Solution: Set X yuan per kilogram of peaches.

3x-5×2.2=2.5

x=4.5

A: Peaches are 4.5 yuan per kilogram.

3. Solution: It was supposed to be shipped x times in the afternoon before it was finished.

5×3+5x=35

x=4

A: It will be delivered four times in the afternoon.

4. Solution: Let the width of the rectangle be x cm.

2×(x+2x)=72

x= 12

12×2=24 (cm)

Answer: The width of a rectangle is 12 cm and the length is 24 cm.

4. Solution: each set of sportswear is X yuan.

15x- 12x=240

x=80

Every sportswear, 80 yuan.

Reference answer:

One,

1、x=6 x=2 x= 1.4

x=0.8 x=4 x=5

Second,

1, solution: let the second train run at x kilometers per hour.

68×4+4x=560

x=72

A: Bus B runs 72 kilometers per hour.

2. Solution: Suppose the distance between two cars is 95 kilometers after X hours.

475-(50+45)x=95

x=4

A: After four hours, the distance between the two cars is still 95 kilometers.

3. Solution: Suppose two ships meet after X hours.

28x+2 1x=392

x=8

A: Eight hours later, the two ships met.

4. Solutions; Set the car to travel x kilometers per hour.

60×( 1.5+2)+ 1.5x = 330

x=80

The car travels 80 kilometers per hour.

3. Solution: Let Xiaoqing run X kilometers per minute.

36 seconds =0.6 minutes

(x+0， 12)×0.6=0.24

x=0.28

A: Xiaoqing runs 0.28 kilometers per minute.

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