Definition Detectives
Variable
A letter that represents an unknown number
12 ÷ 3 + 2
6
Solve for x
12x = 84
x = 7
Determine whether the following statement is true or false:
15 + 9 − 4 = 24 − 4
True
20 = 20
Find the mean, median, and range of:
4, 6, 8
Mean: 6
Median: 6
Range: 4
Constant
A number that does not change
18 − 2 × 4
10
Solve for x
x + 12 = 30
x = 18
Double check if this equation is correct:
x + 9 = 22, x = 4
it is incorrect, x = 13
Find the mean, median, and range of:
2, 5, 5, 9, 11
Mean: 6.4
Median: 5
Range: 9
Substitute
Replace variable with a number
(3 + 4) × 2
14
3x + 12 = 30
x = 6
Double check if this equation is correct:
4x = 36, x = (5+4)
It is correct.
x = (5+4) = 9
Find the mean, median, and range of:
3, 7, 7, 10, 12, 15
Mean: 9
Median: 8.5
Range: 12
Preserve equality
Keep both sides equal by doing the same operation
6+2×(52−3)÷4
17
4(2x+3)−5=25
x = 2
Double check if this equation is correct:
x ÷ 5 = 13, x = 65
x = 65
Find the mean, median, and range of:
3, 7, 7, 10, 12, 15
Mean: 12.3 (rounded)
Median: 10
Range: 14
Isolate
Get variable alone
18÷(3+3)×42−5
43
3(3x−4)+2=20
x = 4
Double check if this equation is correct:
6x + 5 = 35, x = 2
Find the mean, median, and range of:
5, 12, 14, 14, 18, 21, 25, 30
Mean: 17.4
Median: 16
Range: 25