6 + 3 (x + 1) ≥ 12-2 (x + 7) solution inequality

6 + 3 (x + 1) ≥ 12-2 (x + 7) solution inequality

6+3x+3≥12-2x-14
3x+2x≥12-14-6-3
5x≥-11
x≥-11/5

How long does it take for a car to travel 45 kilometers per hour from city a to city B and arrive in 4 hours. When it comes back, its speed will increase by one ninth?

4×45÷[45×(1+1/9)]=3.6
It takes 3.6 hours

In the Pentagon ABCDE, angle a = angle c = angle d = angle e = 120 degrees, angle B degree?

Sum of inner angles of polygon = 180 ° x (n-2)
180°×（5－2）＝540°
540°－（120°X4）＝60°
∠B＝60°

A car delivered goods to the mountain area, traveling 42 kilometers per hour, arriving in 6 / 7 hours. It took only 2 / 4 hours to return to the original road, returning to the mountain area
How many kilometers per hour does the car travel on its return?

Travel 42 kilometers per hour and arrive in 6 / 7 hours. The total distance is:
42 × 6 / 7 = 36 (km)
It takes only two fourths of an hour to return from the original route, and the speed of return can be obtained as follows:
36 △ 2 / 4 = 72 (km / h)

If a is a rational number, compare a with 2A
Such as the title

When a is greater than 0
A is less than 2A
A is equal to 0
When a is less than 0
A is greater than 2A
Discussion by situation

The express train starts from place a and the local train starts from place B at the same time. After 4 hours of meeting, they continue to move forward at the original speed. After another 5 hours, it's a pity
The local train is only 20 kilometers away from a, and the express train is 120 kilometers away from B. how many kilometers is the distance between a and B? What are the speeds of the fast and slow trains?

Two cars travel the whole journey every hour
1 △ 4 = 1 / 4
Five hours after the meeting, the whole journey was completed
1 / 4 × 5 = 5 / 4
Five hours is more than the whole journey
120-20 = 100 (km)
The whole process is
100 (5-1 / 4) = 400 (km)
The express runs every hour
(400 + 120) / (4 + 5) = 520 / 9 (km)
The local train runs every hour
(400-20) / (4 + 5) = 380 / 9 (km)

The rectangular coordinate equation is transformed into polar coordinate equation
y^2=6x

Let the polar coordinates of any point on the curve be (ρ, θ)
Then x = ρ cos θ, y = ρ sin θ
Substituting into rectangular coordinate equation
ρ^2(sinθ)^2=6ρcosθ
One ρ is eliminated on both sides
ρ=6cotθcscθ

A batch of cement is required to be transported in three days. 114 tons were transported in the first day, the remaining 2 / 7 were transported in the second day, and half of this batch of cement was transported in the third day
After the first day, how many tons are left?

Suppose the total amount of cement x, 114 + 2 / 7 × (X-114) + 1 / 2 * x = x, the solution is x = 684, and the answer is 570

In o-abc, OA, OB and OC are perpendicular
As shown in the figure, in the triangular pyramid o-abc, OA, OB and OC are perpendicular to each other. It is known that ∠ OBC = 30 degrees, and the straight line Ca and plane AOB form an angle of Θ

(1)
∵OB⊥OA OB⊥OC
Ψ ob ⊥ planar OAC
∵ AC ∈ planar OAC
∴OB⊥AC
(2)

For a batch of goods, 20% of them were transported in the first time, 6 tons in the second time, and 2 tons less in the third time than in the previous two times. At this time, one third of the remaining goods were not transported. How many tons are there in this batch of goods?
The process of solving the equation Ask for the right answer Is it too demanding? Well, just the process

There are x tons in this shipment
20%X+6+（20%X+6-2）+1/3X=X
X=37.5