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Please tell me the number four and five instructions are solve the system of simultaneously equation by using the substitution method 100 points please help

Please tell me the number four and five instructions are solve the system of simultaneously equation by using the substitution method 100 points please help class=

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alex00044442222
4. 3x+(-x)=4
3x-x=4
2x=4
x=4/2
answers:
x=2
y=-2


5.
y=x-1
4x-y=19
-x+y=-1
4x-y(cross the y’s out they cancel eachother)=19
3x=18
x=6
-6+y=-1
y=-1+6
y=5
answers:
x=6
y=5
learenceiweabudike

Answer:

1) x = 2 and y = -2

2) x = 6 and y = 5

3) x = 2 and y = -4

Step-by-step explanation:

1) 3x + y = 4

since y = -x subtitute it in the equation

3x + (-x) = 4

3x - x = 4

2x = 4

x = 4\2

x = 2

y = -2

2) 4x - y = 19

since y = x - 1 subtitute it in the equation

4x - (x - 1) = 19

4x - x + 1 = 19

3x = 19 - 1

3x = 18

x = 18\3

x = 6

y = 6 - 1 = 5

3) y = 3x - 10

y - 3x = -10

since 2x + y = 0

thus y = -2x subtitute in equation

-2x - 3x = -10

-5x = -10

x = -10\-5

x = 2

y = -2 * 2 = -4

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