7th Grade Math

Lesson 2B Multiplication and Division Equations 217

Multiplication Property of Equality

Words If you multiply each side of an equation by the same

number, the two sides remain equal.

Examples Numbers Algebra

3 = 3 _ 4 x = 7

3 (-6) = 3 (-6) _ 4 x (4) = 7 (4)

• 18 = - 18 x = 28

Solve Division Equations

Solve _-a 4 = -9.

_a

• 4 = -^9 Write the equation.
  _a


• 4 (-4) = -^9 (-4)^ Multiplication Property of Equality
  a = 36 - 9 · (-4) = 36

e.

y

_- 3 = - 8 f. _m 5 = - 7 g. 30 = _-b 6

A formula is an equation that shows the relationship among certain

quantities. One of the most common formulas is the equation d = rt,

which gives the relationship among distance d, rate r, and time t. The

formula can also be written as r = _dt or t = _d

r^.

DISTANCE The distance d Tina travels in her car while driving

60 miles per hour for 3 hours is given by the equation _d 3 = 60.

How far did she travel?

_d 3 = 60 Write the equation.

_ 3 d (3) = 60 (3) Multiplication Property of Equality

d = 180 60 · 3 = 180

Tina traveled 180 miles.

h. ANIMALS A Fitch ferret has a mass of about 2 kilograms. To

find its weight in pounds p, you can use the equation

p

_ 2 = 2.2.

How many pounds does a Fitch ferret weigh?

Everyday Use

Formula A plan or method

for doing something.

Math Use

Formula An equation that

shows the relationship

among certain quantities.

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