The following equations 2x-y-2 = 0 and 4x-3y-8 = 0 are solved by addition subtraction elimination method It's a concrete process

The following equations 2x-y-2 = 0 and 4x-3y-8 = 0 are solved by addition subtraction elimination method It's a concrete process

2x-y-2=0………… （1）
4x-3y-8=0………… （2）
(1) + 1
4x-2y-4=0………… （3）
(3) 2
y+4=0
y=-4………… （4）
Substituting (4) into (1) yields:
2x-(-4)-2=0
Namely:
2x=-2
x=-1
So x = - 1
y=-4

To solve the equations {3x + 2Y = a 2x + 3Y = B, if x + y is required, which of the following methods is the most convenient
A. Substituting elimination method B. addition and subtraction elimination method C. the two methods are the same D. none of the above is correct

Solution B,
Cause 3x + 2Y = a
2x+3y=b
The sum of the two formulas leads to
5x+5y=a+b
Namely
5（x+y）=a+b
That is, x + y = (a + b) / 5

(3x-y) / 5 = (2x + 3Y) = - 1

3x-y=-5
∴y=3x+5
∴2x+3y=2x+9x+15=-1
∴x=-16/11
y=3x+5=7/11

If x is equal to y in the solution of the system of equations {x-3y = k-25x-3y = k, then K is equal to () is a process

Substituting x = y into the system of equations
x-3y=k-2
5x-3y=k
The results are as follows
x-3x=k-2
5x-3x=k
Namely:
-2x=k-2 (1)
2x=k (2)
(1) + (2) the formula is as follows:
0=2k-2
2k=2
k=1