Junior one math problem, with the equation solution, fill in the blanks, only write the answer! Only write the equation formula! 1. It takes 55 seconds for a bus to cross the 690 meter long bridge and 45 seconds to cross the 490 meter long tunnel at the same speed 2. A city has a population of 4.2 million. In order to control the population growth rate within 1% one year later, a population plan is formulated: the urban population growth rate is controlled at 0.8%, and the rural population is controlled at 1.1%. How many people are the urban population and the rural population in a city? 3. The distance between a and B is 448 km. A local train starts from a and runs 60 km per hour, while an express train starts from a and runs 80 km per hour. How many hours should the local train start to reach B at the same time? 4. The train was blocked on the way for six minutes, and then the speed was increased from 40 km / h to 50 km / h. Q: how many km can we make up for the delay? 5. A clock is 3 minutes slower than the standard time every hour. If it is aligned with the accurate time at 6:30 in the morning, then the clock indicates 12:50 at noon. What is the accurate time?

Junior one math problem, with the equation solution, fill in the blanks, only write the answer! Only write the equation formula! 1. It takes 55 seconds for a bus to cross the 690 meter long bridge and 45 seconds to cross the 490 meter long tunnel at the same speed 2. A city has a population of 4.2 million. In order to control the population growth rate within 1% one year later, a population plan is formulated: the urban population growth rate is controlled at 0.8%, and the rural population is controlled at 1.1%. How many people are the urban population and the rural population in a city? 3. The distance between a and B is 448 km. A local train starts from a and runs 60 km per hour, while an express train starts from a and runs 80 km per hour. How many hours should the local train start to reach B at the same time? 4. The train was blocked on the way for six minutes, and then the speed was increased from 40 km / h to 50 km / h. Q: how many km can we make up for the delay? 5. A clock is 3 minutes slower than the standard time every hour. If it is aligned with the accurate time at 6:30 in the morning, then the clock indicates 12:50 at noon. What is the accurate time?

1.205 M
two
3.(448-60x)/60=448/80
4.40*6/50
5.13:09

Where the solution is x = 0 in the following equation is:
A.2(4X+3)-6=0
B.0.3X-4=5.7+1
C.3x+1/2 -4x-1/3=0
D.1/101+1=-2x

Choose a

When the equation a (A-2) x = 4 (A-2) has a unique solution, what is the value range of a?

From a (A-2) x = 4 (A-2), a & sup2; x-6ax + 8 = 0
① When a = 0, there is no solution
② If a ≠ 0, ⊿ = 36a & sup2; - 32A = 0, then a = 0 (rounding) or a = 8 / 9
So a = 8 / 9