Given that X and y satisfy x ^ 2 + y ^ 2 = 2x + Y-5 / 4, find the value of x ^ 2-2xy-y ^ 2 Encountered problems, please give me more advice

Given that X and y satisfy x ^ 2 + y ^ 2 = 2x + Y-5 / 4, find the value of x ^ 2-2xy-y ^ 2 Encountered problems, please give me more advice

The formula is, (x-1) ^ 2 + (Y-1 / 2) ^ 2 = 0, so x = 1, y = 1 / 2, so x ^ 2-2xy-y ^ 2 = - 1 / 4

Move the decimal point of a decimal one place to the right, the new number is 25.56 more than the original number, what is the original number?

Move the decimal point one place to the right --- 10 times the original
25.56÷（10-1）=2.84
The original number is 2.84

The speed ratio of the freight car to the passenger car is 5:7, and the distance between a and B is several thousand meters?
Not equations, but formulas!
The passenger car and the freight car drive in the opposite direction from the midpoint of a and B at the same time. Five hours later, the passenger car arrives at a, and the freight car is 60 kilometers away from B. It is known that the speed ratio of the freight car to the passenger car is 5:7. How many kilometers is the distance between a and B?

The speed ratio of freight cars to passenger cars is 5:7
The distance ratio is 5:7
Let the distance between a and B be 1
The distance between a and B is 1 / 2
Then the distance of line B is 1 / 2 * 5 / 7 = 5 / 14
Then the remaining distance of B is 1 / 2-5 / 14 = 2 / 14 = 1 / 7
Then the distance between a and B: 60 / (1 / 7) = 420 km

Let X and y be real numbers and satisfy (x-1) ^ 3 + 2008 (x-1) = - 1, (Y-1) ^ 3 + 2008 (Y-1) = 1, then x + y=

x+y=2(x-1)^3+2008(x-1)=-1(y-1)^3+2008(y-1)=1(x-1)^3+2008(x-1)+(y-1)^3+2008(y-1)=0(x-1)^3+(y-1)^3+2008(x-1+y-1)=0((x-1)+(y-1))((x-1)^2-(x-1)(y-1)+(y-1)^2)+2008(x+y-2)=0(x+y-2)((x-1)^2-(x-1)(y-1)+(y-1)^...

The two trains start from both places at the same time and run in opposite directions. Car a runs 63 kilometers per hour, car B 54 kilometers per hour, and the two trains meet in 4.8 hours
Please, if you can't write it, you're dead

63X4.8+54x4.8=302.4+259.2=561.6KM

The average of the three numbers is 50. The ratio of the three numbers is 3:7:5. They are______ 、______ And______ ．

50 × 3 = 150150 × 33 + 7 + 5 = 30150 × 73 + 7 + 5 = 70150 × 53 + 7 + 5 = 50; answer: the three numbers are 30, 70 and 50 respectively

The speed of car a is seven eighths of that of car B. the two cars are facing each other at the same time from station a and B, and they meet at 30 kilometers away from the midpoint. What is the distance between the two stations?
How many kilometers did a travel when they met? Anxious

Distance 30x2 ÷ (8-7) x (8 + 7) = 60x15 = 900km
A walked 900 △ (8 + 7) X7 = 420 km
If you don't understand this question, you can ask,

How to prove that 1 + 2 equals 3
The reasoning process of proving that 1 + 2 is equal to 3

What is the known condition? Without known condition, it can't be proved!

On the map of China with a scale of 1:6000000, the distance between the two places is 10 cm. The two trains leave from the two places at the same time, and they meet six hours later. Car a travels 55 kilometers per hour, and how many kilometers per hour does car B travel?

Actual distance: 10 △ 1 / 6000000 = 6000000 cm = 600km
B speed: 600 △ 6-55
=100-55
=45 km

In the tetrahedral ABCD, ab = 3, AC = ad = 2, and ∠ DAC = ∠ BAC = ∠ bad = 60 °. The proof is plane BCD ⊥ plane ADC

It is proved that: take the midpoint e of CD, connect be ∵ AC = ad, CE = ed, ∠ DAC = 60 ≁ AE ⊥ CD, AC = ad = CD ≁ CD = 2, CE = ed = 12CD = 1, AE2 = ac2-ce2 = 4-1 = 3bc2 = BD2 = ac2 + ab2-2ac · BCCs ∠ BAC = 4 + 9-2 · 2 · 3 · cos60 ° = 7, △ BCD is isosceles triangle