Basic exercises

1.x+2 x-2 (x+2)+x+(x-2)=66

2.a+3 ^ 3(9-3)= a+3

3. Solution: Set up two classes to plant X trees.

x+2x+ 1=3 1

Solve this equation and get x= 10.

Category I: 10×2+ 1=2 1 (plants)

Test: x= 10 accords with the equation and the meaning of the question.

Answer: Class One planted 2 1 tree, and Class Two planted 10 tree.

4. Solution: Set * * * to buy fruit X boxes.

30x=40( 1/2x+5)

Solve this equation and get x=20.

Test: x=20 accords with the equation and the meaning of the question.

The fruit merchant bought 20 boxes of fruit.

Comprehensive application

5. Solution: The train body is x meters long.

1200×4=4700+x

Solve this equation and get x= 100.

Test: x= 100 conforms to the equation and the meaning of the question.

Attendant: Body length 100 meter.

6.( 1)

Solution: Let's set out and catch up with Xiaoming in X minutes.

80×(5+x)= 180x

Solve this equation and get x=4.

Test: x=4 accords with the equation and the meaning of the question.

A: Catch up with Xiaoming after 4 minutes' departure.

(2)

Solution: suppose it is still x meters away.

180×4+x= 1000

Solve this equation and get x=280.

Test: x=280 conforms to the equation and the meaning of the question.

A: It's still 280 meters away.

Ensure that all watchtower owners adopt and agree.