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Big Ideas Math: Modeling Real Life, Grade 8

BI

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

4. Rewriting Equations and Formulas

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Exercise 14 Page 29

Apply inverse operations to isolate y.

y=35-15x

Practice makes perfect

To solve the given literal equation for y, we will use the Properties of Equality to apply inverse operations on the equation. Remember, only like terms can be combined.

3x+1/5y=7

LHS-3x=RHS-3x

3x+1/5y-3x=7-3x

Subtract term

1/5y=7-3x

LHS * 5=RHS* 5

(1/5y)5=(7-3x)5

▼

Simplify left-hand side

CommutativePropMult

Commutative Property of Multiplication

(1/5)5y=(7-3x)5

FracMultDenomToNumber

a/5* 5 = a

1(y)=(7-3x)5

Identity Property of Multiplication

y=(7-3x)5

Now, we can use the Distributive Property to simplify the equation even further.

y=(7-3x)5

Distribute 5

y=35-3x(5)

Multiply

y=35-15x

Subchapter links

Try It p.26-27

Self-Assessment for Concepts & Skills p.27

Self-Assessment for Problem Solving p.28

Review & Refresh p.29

Concepts, Skills, & Problem Solving p.29-30