ALGEBRA NOTES (7th)
Solving Equations (1-step)
x + 4 = 12 à you do the opposite, so subtract 4 from both sides
-4 -4
x = 8 à your answer is 8
8 + 4 = 12 à check your work by plugging in your answer for x.
x – 5 = 13 à you do the opposite, so add 5 to both sides
+ 5 +5
x = 18 à your answer is 18
18 – 5 = 13à check your work by plugging in your answer for x.
3x = 15 à you do the opposite, so divide both sides by the coefficient (3)
3 3
x = 5 à your answer is 5
3 (5) = 15 à check your work by plugging in your answer for x.
= 6 à you do the opposite, so multiply both sides by 4
x = 24 à your answer is 24
24 = 6 à check your work by plugging in your answer for x.
4
Solving Equations (2-step)
4x – 9 = -29 à first, add 9 to both sides
+ 9 + 9
4x= -20 àsecond, divide both sides by 4
4x = -20
4 4
x = -5 à your answer is –5
4 (-5) – 9 = -29
-20 –9 = -29 à check your work by plugging in your answer for x.
5x + 8 = 28 à first, subtract 8 from both sides
- 8 -8
5x= 20 àsecond, divide both sides by 5
5x = 20
5 5
x = 4 à your answer is 4
5(4) + 8 = 28
20 + = 28 à check your work by plugging in your answer for x.
+ 12 = 3 à first, subtract 12 from both sides
-12 -12
= -9 àsecond, multiply both sides by 4
x =-36 àyour answer is –36
+ 12 = 3 à check your work by plugging in your answer for x.
-9 + 12 = 3