Solve this system of equations by substitution: x + 2y = 9 y = -x + 3?

Answer 1

x + 2y = 9
y = - x + 3

x + 2(3 - x) = 9
x + 6 - 2x = 9
- x = 3
x = - 3

y = 3 + 3
y = 6

x = - 3 , y = 6

Answer 2

Substitute (replace) the y value in one equation with the y value from the other equation:
x + 2y = 9
x + 2 (-x + 3) = 9
x -2x + 6 = 9
-x = 3 -> x = -3

Put the x value to any original equation:
x + 2y = 9
-3 + 2y = 9
2y = 12
y = 6

Answer 3

You have two equations:

x + 2y = 9 and
y = -x +3

When you have two equations with two variables, the goal is to solve for the values of the x and y variables. With the substitution method, you will solve for one of the variables in one equation, then plug that into the same variable in the other equation. Since y is already solved in the second equation listed here, we will plug that into the y value into the first equation. We get:

x + 2(-x + 3) =9

Simplifying step by step, we get:

x -2x + 6 = 9
-x = 3
x = -3

Now that we know the value of the x variable, we can plug this value into anyone of the original equations to find the y value. Using the first equation:

-3 + 2y = 9

Simplifying, we get:

2y = 12
y = 6

Therefore, your final answer to this problem is:
x = -3
y = 6

Answer 4

x + 2y = 9 y = -x + 3


x + 2 (-x +3) = 9
x -2x + 6 =9
-x=3


x=-3
y= 6

i think
just plug in -x +3 wherever a y is

Answer 5

From 3x - y = -7, y = 3x + 7, which you substitute into x + y = -9, so: x + y = -9, so x + (3x + 7) = -9, so x + 3x + 7 = -9, so 4x = - 16, so, x = -4, and y = 3x + 7 = -5. Hope this helps, Twiggy.

Answer 6

x+2y=9
y=-x+3
x+2(x+3)=9
x+2x+6=9
3x+6=9
-6 -6
3x=3
x=1

Answer 7

this is simple once you learn how.

just put -x+3 in for y in the first equation.

x+2(-x+3)=9

solve for x.

x= -3



then with x you can solve for y

Answer 8

x=-3
y=6