First, multiple-choice questions 1. B
2..B.
3.D
4.D
5..A.
6.B。
7.D。
8.C。
9.D。
10. Fill in the blanks
1.x=6/5，
y=-7/5
2.m=0
n= 1
3.x= 1/ 10+3y/5
4.30
six
5. 100 yuan
50 yuan
6. The value of a is 18.
7. This two-digit number is 23.
8.3 children, 1 1 pear.
9.
-2/3
10.3 III. Solving problems (1)x=-29/2
y=-25/7
(2)x= 1/3
y=-32.k=4
3. Because X and Y are solutions of four equations, X = 1 can be solved from 5x+y=3 and x-2y=5, Y =-2 can be brought into AX+5Y = 4 and A- 10 = 4, so a= 14 can be brought into 5x.
x
Meters, apprentice maintenance once an hour.
y
Rice; Later, the master overhauled it every hour.
2x
rice. Countable equation: 6x+6y
=
2 10
, 2 *(2 times)
=
6y
; Solution: x
=
2 1
，y
=
14
At first, the master overhauled it every hour.
2 1
Meters, apprentice maintenance once an hour.
14
rice. 5. Solution: Team A originally planned daily maintenance.
x
Km, team b originally planned to repair it every day.
y
According to the original plan, Team A and Team B need to cooperate.
50
Day; In fact, Team A was repaired.
50
Day, in which
30
Repair every day.
x
Kilometers, in addition
50-30
=
20
Repair every day.
x+0.6
Km, team B * * * has been repaired.
50- 10
=
40
Day, in which
30
Repair every day.
y
Kilometers, in addition
40-30
=
10
Repair every day.
y+0.4
Kilometer; Countable equation: 50(x+y)
=
200
，30x+20(x+0.6)+30y+ 10(y+0.4)
=
200
; Solution: x
=
2.4
，y
=
1.6
Team a was going to repair it every day.
2.4
Km, team b originally planned to repair it every day.
1.6
Kilometers 6. Because Xiaoying got the correct solution, she substituted the values of X and Y into the equation.
ax+by=9
And 3x-cy=-2: 2a+4b=9.
Formula (1)
3*2-4*c=-2
Type (2)
The conclusion here is that
c=
Then, because
Xiao Liang copied C wrong.
X=4，y=- 1。
You can know because A and B didn't copy correctly.
So his solution still satisfies ax+by=9.
Bring his x, y into
get
4a-b=9
(3) So
Pass (1) and (3)
work out
a=
5/2,
b=
1, so
a=
5/2,
b=
1
c=
2