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Big Ideas Math Geometry, 2014

BI

Big Ideas Math Geometry, 2014 View details

Chapter Test

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Exercise 9 Page 119

Use inverse operations until you have fully isolated x.

x=6

Practice makes perfect

To solve the equation, we have to isolate x on one side using inverse operations. To begin with, we want to collect all of the constants on one side of the equation. First, we have to eliminate the 3 from in front of the parenthetical factor. To do it, we will use the Distributive Property.

3(7x-9)-19x=- 15

Distribute 3

3(7x)- 3(9)-19x=- 15

Multiply

21x-27-19x=- 15

Next, we will combine the like terms, 21x and 19x, by subtracting the second term from the first one.

21x-27-19x=- 15

Subtract term

2x-27=- 15

The inverse operation to subtraction is addition, so to eliminate 27 from the left-hand side we have to add 27 to both sides of the equation.

2x-27=- 15

LHS+27=RHS+27

2x-27 + 27=- 15 + 27

Add terms

2x=12

Finally, we have to eliminate 2 from in front of x. Since multiplication and division are inverse operations, we have to divide by 2.

2x=12

.LHS /2.=.RHS /2.

2x/2=12/2

Calculate quotient

x=6

Subchapter links

Exercises p.119