In order to measure the distance between points a and B at both ends of the pond, Xiaoming chooses three points o, D and C on the ground, so that OA = OC, OB = OD, and points a, O, C and B, O, D are in a straight line. Xiaoming thinks that as long as the distance between DC is measured, the distance between ab can be known. Do you think Xiaoming's practice is correct? Please give reasons

In order to measure the distance between points a and B at both ends of the pond, Xiaoming chooses three points o, D and C on the ground, so that OA = OC, OB = OD, and points a, O, C and B, O, D are in a straight line. Xiaoming thinks that as long as the distance between DC is measured, the distance between ab can be known. Do you think Xiaoming's practice is correct? Please give reasons

The reasons are as follows: as shown in the figure, connecting AB, in △ AOB and △ cod, OA = OC ∠ AOB = ∠ codob = OD, ≌ AOB ≌ cod (SAS), ≌ CD = ab

(2x + 2, y + 1) (2x + 2, y minus 1) is equal to the square of 31, (x + y)
What is the square of (x + y)

Because,
(2x＋2y＋1)(2x＋2y－1)
=(2x+2y)²-1²
=31
So, 4 (x + y) ² = 32
So, (x + y) ² = 8

If equation 3 / 2x + 4 equals - 1-1 / 2x and equation a + x equals - 2x + 6 about X have the same solution, find the value of A-10

(3/2)x+4=-1-(1/2)x
2x=-5
x=-5/2
Substitute x = - 5 / 2 into a + x = - 2x + 6 to get
a-5/2=-2*(-5/2)+6
So a = 27 / 2, so A-10 = 7 / 2

If 2x and 2-x are opposite to each other, what is x equal to?
Can you make it more clear? I don't quite understand

The sum of two opposite numbers equals 0
2x+(2-x)=0
2x+2-x=0
x+2=0
x=-2

When x=______ The values of X-1 and 3-2x are opposite to each other

The value of ∵ X-1 and 3-2x are opposite to each other, X-1 + 3-2x = 0, that is - x + 2 = 0, the solution is x = 2

If the value of 2x + 6 and the value of 3 + 2x are opposite to each other, then the value of X should be equal to---

2x+6=-（3+2x）
4x=-9
x=-9/4

When x equals (), the values of (2x-3) / 5 and 2 / 3-3 are opposite to each other

The equation can be obtained from the meaning of the question
（2x-3）/5+(2/3-3)=0
(2x-3)/5-7/3=0
(2x-3)/5=7/3
15(2x-3)=35
30x-45=35
30x=80
x=8/3

1/4x-3y=8 y-2x=5
Solving equations

1/4x-3y=8
2x-24y=64 ①
y-2x=5 ②
① + 2 is - 23y = 69
Y = - 3 substituting y = - 3 into ②
We get - 3-2x = 5
2x=-3-5
2x=-8
x=-4

2x-y-2 = 0 4x-3y-8 = 0

2x-y-2=0
2x-y=2①
4x-3y-8=0
4x-3y=8②
①×2
4x-2y=4③
③-②
y=-4
x=-2

{2x-3y=-8 4x+3y=20

2x-3y=-8 (1)
4x+3y=20 (2)
(1) + (2) get
6x=12
∴x=2
Substituting x = 2 into (1) yields
4-3y=-8
∴y=4
∴x=2
y=4