Vocabulary
What is a variable?
A variable is an unknown that is represented by a symbol or a letter.
What is the inverse operation of addition?
Subtraction
What is the inverse operation of subtraction?
Addition
What is the inverse operation of multiplication?
Division
What is the inverse operation of division?
Multiplication
What does inverse operation mean? Give an example.
Inverse operation means performing the opposite operation. For example, the opposite of addition is subtraction.
x + 5 = 12
x = 7
x - 2 = 19
x = 21
32x = 4
x = 8
5 = x / 4
x = 20
What does reciprocal mean? Give an example.
Reciprocal means the numerator and denominator are flipped. For example, the reciprocal of 2/3 is 3/2.
32 = x + 17
x = 15
27 = x - 54
x = 81
6.3 = 0.9x
x = 7
x / 4 =17
x = 68
What are the steps for double checking?
First, rewrite the problem. Then, substitute for the answer for the variable. Lastly, solve to see if both sides are equal.
x + 3.25 = 32.4
x = 29.15
x - 42.7 = 7.25
x = 49.95
3 1/2r = 28
r = 8
4.7 = x / 3.2
x = 15.04
What is the difference between an expression and an equation?
An equation has an equal sign and an expression does NOT.
Kevin and May together have $756.80. If Kevin has $489.50, how much does May have? Write and solve an addition equation to find how much money belongs to May.
x + $489.50 = $756.80
x = $267.30
Lance is 15 years old. This is 6 years younger than his sister Vanessa. Write and solve a subtraction equation to find Vanessa’s age.
x - 6 = 15
x = 21
A game store is having a sale and selling 4 games for $60, including tax. Write and solve a multiplication equation to find how much one game costs.
4g = $60
g = $15
A model plane is 1/48 the size of the actual plane. If the model plane is 28 inches long, how long is the actual plane? Write the equation and solve.
x / 48 = 28
x = 1,344