If A2 + B2 + c2-ab-3b-2c + 4 = 0, then the value of a + B + C is______ ．

If A2 + B2 + c2-ab-3b-2c + 4 = 0, then the value of a + B + C is______ ．

A2 + B2 + c2-ab-3b-2c + 4 = 0a2-ab + 14b2 + 34 (b2-4b + 4) + c2-2c + 1 = 0 (a-12b) 2 + 34 (b-2) 2 + (C-1) 2 = 0 〈 a-12b = 0, 34 (b-2) = 0, C-1 = 0 〈 a = 1, B = 2, C = 1, then a + B + C = 4

A freight car and a passenger car leave 504km away from each other at the same time, and meet in 4.5 hours. The passenger car runs 64km per hour, and the freight car runs how many km per hour?

504 △ 4.5-64 = 112-64 = 48 (km) a: the freight car travels 48 km per hour

A passenger car and a freight car leave from a and B at the same time. The speed of the freight car is 45 times that of the passenger car. After 14 kilometers of the whole journey, the freight car runs 28 kilometers to meet the passenger car. How many kilometers are there between a and B?

The distance between a and B is (14 + 28) km, and (14 + 28) km

Buses and trucks travel from two places 852km apart and face each other at the same time. When they meet, the distance of buses is 189km less than twice that of trucks. How many kilometers do buses and trucks travel?

Suppose the freight car runs for X km, then the passenger car runs for 2x-189 km, x + 2x-189 = 852, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 3x = 852 + 189, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; 3x = 1041, & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; X = 347; the passenger car runs for 2 × 347-189

It takes Li Ping one hour to ride a bicycle from home to the county. Because there are 3.6 kilometers of uneven roads on the way, the speed of this section of road is equivalent to 3 / 4 of the original speed,
So it's 12 minutes late. How many kilometers is it from Li Ping's home to the county?

Speed ratio 4:3
The time ratio is 3:4
What is the planned time of 3.6km
12x3 ÷ (4-3) = 36 minutes = 0.6 hours
3.6÷0.6x1＝6km

Li Ming rides a bicycle from his home to the city. The plan is 3 hours. Due to the uneven road of 6 kilometers on the way, the speed is 75% of the original speed, so it is several thousand meters from Li Ming's home to the county seat 12 minutes late
The answer seems to be 30 kilometers, but I don't know what to do?

6 divided by 3 / 4 = 8 km, this is to take this section of road, equivalent to 8 km level road
12 minutes = more than 2 kilometers
12 divided by 2 = 6 min / km
3 hours by 6 minutes / km = 30 km

Zhang Xiang started from school and rode his bike to the county. He walked for a while due to road construction, and arrived at the county after 1.5 hours. His speed was 15 km / h
The average speed of walking is 5km / h, and the total length of the journey is 20km. How long does it take for him to drive and walk respectively? We need to use binary linear equations

Set X hours for cycling and Y hours for walking
x+y=1.5
15x+5y=20
The solution is: x = 1.25, y = 0.25

It was originally planned to take 5 hours and 30 minutes for Li Ping to ride a bicycle from his home to the county. Because there was 335 kilometers of uneven road on the way, the speed of walking on this uneven road was 34 times of the original speed, so he arrived 12 minutes late. How many kilometers is the distance between Li Ping's home and the county?

5 hours, 30 minutes = 5.5 hours, 12 minutes = 0.2 hours. The planned time for walking on uneven roads is 0.2 △ 43 − 1, = 0.2 △ 13, = 0.6 hours. The original speed for walking on uneven roads is 335 △ 0.6 = 6 km / h. The distance between Li Ping's home and the county is 6 × 5.5 = 33 km. A: the distance between Li Ping's home and the county is 33 km

Someone originally planned to cycle from a to B at a speed of 12 kilometers per hour,
In this way, he could arrive at the appointed time. However, he delayed his original planned departure time by 20 minutes due to something, so he had to move forward at the speed of 15 kilometers per hour. As a result, he arrived at B 4 minutes earlier than the appointed time, seeking the distance between ab and B

Suppose the distance between the two places is x, X / 12 = x / 15 + (20 + 4) / 60, x = 24 km

In triangle ABC, if a ^ 2-B ^ 2-C ^ 2 = BC, find the size of ∠ a
In triangle ABC, if a ^ 2-B ^ 2-C ^ 2 = - BC, find the small of ∠ a
Be quick,

Cosa = (b ^ 2 + C ^ 2-A ^ 2) divided by 2BC = - 1 / 2
Therefore, a = 120
If a ^ 2-B ^ 2-C ^ 2 = - BC
Then ∠ a = 60