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Big Ideas Math: Modeling Real Life, Grade 8

BI

Big Ideas Math: Modeling Real Life, Grade 8 View details

Chapter Review

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Exercise 12 Page 34

Gather all of the variable terms on one side of the equation and all of the constant terms on the other side.

n = 6

Practice makes perfect

To solve an equation, we should first gather all of the variable terms on one side and all of the constant terms on the other side using the Properties of Equality. In this case, we need to start by using the Subtraction Property of Equality.

3n + 12 = 30

LHS-12=RHS-12

3n + 12 - 12 = 30 - 12

Subtract terms

3n = 18

Now we can use the Division Property of Equality.

3n = 18

.LHS /3.=.RHS /3.

3n/3 = 18/3

CancelCommonFac

Cancel out common factors

3n/3 = 18/3

Simplify quotient

n = 18/3

Calculate quotient

n = 6

The solution to the equation is n = 6. We can check our solution by substituting it into the original equation.

3n + 12 = 30

n= 6

3( 6) + 12 ? = 30

Multiply

18 + 12 ? = 30

Add terms

30=30 ✓

Since the left-hand side is equal to the right-hand side, our solution is correct.

Subchapter links

1 Solving Simple Equations p.33

2 Solving Multi-Step Equations p.34

3 Solving Equations with Variables on Both Sides p.34-35

4 Rewriting Equations and Formulas p.35