Core Connections: Course 3
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1. Section 7.1
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Exercise 33 Page 292

Practice makes perfect
We are asked to solve the following equation for x and check our solution. 3x/4-2(4+2x)=-1/2x+1/4 Let's do it!

Solving the Equation

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 Distributive Property to simplify the left-hand side of the equation.

3x/4-2(4+2x)=-1/2x+1/4
3x/4-2(4)-2(2x)=-1/2x+1/4
3x/4-8-4x=-1/2x+1/4

Now we can continue to solve using the properties of equality.

3x/4-8-4x=-1/2x+1/4
3x/4-4x=-1/2x+1/4+8
3x/4-4x+1/2x=1/4+8
â–¼
Simplify left-hand side
3x/4-4x/1+1/2x=1/4+8
3x/4-4x* 4/1* 4+1/2x=1/4+8
3x/4-4x* 4/1* 4+1x/2=1/4+8
3x/4-4x* 4/1* 4+1x* 2/2* 2=1/4+8
3x/4-16x/4+2x/4=1/4+8
3x-16x+2x/4=1/4+8
- 11x/4=1/4+8
â–¼
Simplify right-hand side
- 11x/4=0.25+8
- 11x/4=8.25

Next, we will use the Multiplication and Division Properties of Equality to isolate x.

- 11x/4=8.25
- 11x/4* 4=8.25* 4
- 11x=8.25* 4
- 11x=33
- 11x/- 11=33/- 11
x=- 3

We found that x=- 3 is the solution to the equation.

Checking Our Solution

To check our solution, we will substitute it into the original equation and simplify. If we end up with a true statement, we will know that our answer is correct. Let's do it!

3x/4-2(4+2x)=-1/2x+1/4
3( - 3)/4-2(4+2( - 3))? =-1/2( - 3)+1/4
- 9/4-2(4-6)? =3/2+1/4
- 9/4-2(-2)? =3/2+1/4
- 9/4+4? =3/2+1/4
- 2.25+4? =1.5+0.25
1.75 = 1.75 ✓

We got a true statement, so our solution is correct!

We will solve the following equation for x and check our solution. - 5/3x+2/5-1/3x+1=0

Solving the Equation

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 will move the constant terms to the right-hand side of the equation.

- 5/3x+2/5-1/3x+1=0
- 6/3x+2/5-1/3x+5/5=0
- 6/3x+7/5=0
- 6/3x=- 7/5
- 6/3x=- 7/5

Now let's simplify both sides of the equation.

-6/3x=- 7/5
- 2x=- 7/5
- 2x = - (5+2/5)
- 2x = - (5/5+2/5)
- 2x = - (1+0.4)
- 2x = - 1.4

Finally, we can use the Division Property of Equality to isolate x.

- 2x=- 1.4
- 2x/- 2=- 1.4/- 2
x=0.7

The solution to the equation is x=0.7.

Checking Our Solution

We can check our solution by substituting it into the original equation.

- 5/3x+2/5-1/3x+1=0
- 5/3( 0.7)+2/5-1/3( 0.7)+1? =0
- 5 * 0.7/3+2/5-1* 0.7/3+1? =0
- 3.5/3+2/5-0.7/3+1? =0
2/5-4.2/3+1? =0
15(2/5)-15(4.2/3)+15(1)? =15(0)
15* 2/5-15 * 4.2/3+15(1)? =15(0)
30/5-63/3+15? =0
6-21+15? =0
0=0 ✓

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