Core Connections: Course 3
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Core Connections: Course 3 View details
3. Section 7.3
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Exercise 115 Page 327

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 can start by using the Multiplication Property of Equality to get rid of the fractions.
1/5x+1/3x=2
15(1/5x+1/3x)=15(2)
15(1/5x)+15(1/3x)=15(2)
15(1)/5x+15(1)/3x=15(2)
15/5x+15/3x=30
3x+5x=30
8x=30
Now we can use the Division Property of Equality to isolate x.
8x=30
8x/8=30/8
x=3.75
To solve the given equation we will use the Multiplication Property of Equality to get rid of the decimals.
x+0.15x=$ 2
100(x+0.15x)=100($ 2)
100x+100(0.15x)=100($ 2)
100x+15x=$ 200
115x=$200
Now we can use the Division Property of Equality to isolate x.
115x=$200
115x/115=$200/115
x=$ 1.739130...
x≈ $ 1.74
We are asked to solve the following equation. x+2/3=x-2/7Let's first get rid of the fractions by using cross multiplication.
x+2/3=x-2/7
3(x-2)=7(x+2)
3x-3(2)=7(x+2)
3x-3(2)=7x+7(2)
3x-6=7x+14
Now we will group all the x-terms and constant terms together on opposite sides of the equation using properties of equality.
3x-6=7x+14
-6 = 4x+14
- 20 = 4x
-20/4=4/4
- 5=x
x=- 5
We are asked to solve the following system of equations. y= 23x+8 & (I) y= 12x+10 & (II) Since both equations are solved for y, we will use the Substitution Method to solve the system. Let's substitute Equation (I) for y into Equation (II).
y= 23x+8 & (I) y= 12x+10 & (II)
y= 23x+8 23x+8= 12x+10
y= 23x+8 6( 23x+8)=6( 12x+10)
y= 23x+8 6( 23x)+6(8)=6( 12x)+6(10)
y= 23x+8 4x+48=3x+60
Now we will solve Equation (II) for x.
y= 23x+8 4x+48=3x+60
y= 23x+8 4x=3x+12
y= 23x+8 x=12
Next, we will substitute 12 for x into Equation (I) and simplify.
y= 23x+8 x=12
y= 23( 12)+8 x=12
y=8+8 x=12
y=16 x=12
We found that the solution to the given system of equations is (12,16).