Substitution Method
Problem |
Directions |
x+2y=-4 y=5x+9 |
The best time to use the substitution method is when you have and equation put in terms of one of the varioables, like in the second part of the question. |
x+2(5x+9)=-4 |
Since you already have one of the equations put in terms of y, you can substitute what it equals in one equation into the other equation in place of the y. |
x+10x+18=-4 |
Then you distribute the two to the 5x and the 9 |
11x+18=-4 |
Next you will combine like terms |
11x=-22 |
To get the variable by itself subtract 18 from both sides of the equation |
x=2 |
To get the value of x divide both sides by 11. |
| x+2y=-4 |
Now you will plug the x value into the original equation and solve for y. |
2y=-6 |
Subtract 2 from both sides of the equation |
| y=-3 x=-2>>>>>(-2,-3) | divide by two and you have your y value so you know now both your y value and your x value |