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Solve Equations using the Division and Multiplication Properties of Equality: example 2.15 · Physics Playground

Exercises Equations and inequalities

Example 2.15 from Elementary Algebra, 2.2 Solve Equations using the Division and Multiplication Properties of Equality

Solve Equations using the Division and Multiplication Properties of Equality: example 2.15

Solve: $− n = 9 .$

Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.

Solution


Remember $− n$ is equivalent to $−1 n$ .
Divide both sides by $−1$ .
Divide.
Notice that there are two other ways to solve $− n = 9$ . We can also solve this equation by multiplying both sides by $−1$ and also by taking the opposite of both sides.
Check:
Substitute $n = −9$ .
Simplify.

Your turn

The book's Try It right after this example: same idea, new numbers. Only the answer is given.

Solve: $− k = 8 .$

How did it go?

PreviousSolve Equations using the Division and Multiplication Properties of Equality: example 2.14 Next Solve Equations using the Division and Multiplication Properties of Equality: example 2.16

From Elementary Algebra (1st edition) by OpenStax (Rice University), section 2.2, licensed under CC BY 4.0. Original at openstax.org. We split the solution into steps; the words, numbers and figures are the book's. OpenStax doesn't endorse this site.