Solve x + 3y = 9
Linear equation, worked out line by line the way a teacher would write it.
Answer
| Solution | y = 3 − x/3 |
Step-by-step solution
5 steps-
1 Givenx + 3 y = 9
Solve for y.
-
2 Subtract x from both sides
An equation stays true as long as you do the same thing to both sides, like adding the same weight to both pans of a balance. Adding or subtracting the same amount on both sides moves a term to the other side, where it appears with the opposite sign.
3 y = 9 - xMove the constant terms to the right.
-
3 Divide both sides by 3
Dividing both sides by 3 undoes the multiplication by 3, so the variable is left on its own. Both sides change in the same way, so the equation stays true (dividing by 0 is the one thing that is never allowed).
y = \frac{9 - x}{3} -
4 Simplifyy = 3 - \frac{x}{3}
-
5 Read off the slope m and the y-intercept b from y = mx + bm = - \frac{1}{3},\quad b = 3
Table of values
| x | y |
|---|---|
| −2 | 11/3 |
| −1 | 10/3 |
| 0 | 3 |
| 1 | 8/3 |
| 2 | 7/3 |
Open this problem in the solver
Change a number or try your own problem: the solver works it out the same way, with a graph and hint mode.