Intro to Solving for Variables

By Emma Davis

Edited by Sophia Layton


Say you’re given an equation in the form ax + b = c. How would you go about solving this for x?


Think of it like you are undoing all the operations in the equation.


Let’s use 3x + 5 = 20 as an example. To solve for x, you want to have x alone on the left side of the equation. So the first step is to undo the addition or subtraction, which in this case, would be the + 5.


To undo addition, subtract the number being added from both sides of the equation. To undo subtraction, add the number being subtracted to both sides.


3x + 5 = 20

- 5 - 5

3x = 15


You should be left with 3x = 15. Now, the next step is to undo any multiplication or division. For this equation, we need to get rid of the 3 that is multiplying the x.


To undo multiplication, divide each side by the coefficient (the number next to the variable- the one that is multiplying it. In this case, the coefficient is 3). To undo division, multiply each side by the divisor.


3x = 15

----------

3

x = 5


You should be left with x = 5. Congrats! You’ve solved it for x. To check your answer, insert the x value (what x ends up equal to) in place of x in the original equation. If the equation is true, you are correct!


3(5) + 5 = 20

15 + 5 = 20

20 = 20


Here are some more examples for reference!


2x - 4 = 12 1/2x + 1 = 21

+4 + 4 - 1 - 1

2x = 16 1/2x = 20

--------- 2(1/2x) = 2(20)

2 x = 40

x = 8


7 views0 comments

Related Posts

See All