solving equations by adding or subtracting pre-algebra lesson 2-5 (for help, go to lesson 2-1.)...
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Vocabulary and Concepts Solving Equations by Adding or Subtracting PRE-ALGEBRA LESSON 2-5 Subtraction Property of Equality You can subtract the same number from each side of an equation Quick Check 2-5 Vocabulary ArithmeticAlgebra 10= 2( 5 ) if a = b 10 – 5 = 2( 5 ) - _____ then a – c = b - _____ c 5TRANSCRIPT
Solving Equations by Adding or SubtractingPRE-ALGEBRA LESSON 2-5
(For help, go to Lesson 2-1.)
Simplify each expression.
1. 3 + 4 – 4 2. 7 + 9 – 7
3. 8 – 2 + 2 4. 6 + 2 – 2
Check Skills You’ll Need
2-5
Bell Work # 9
Solving Equations by Adding or SubtractingPRE-ALGEBRA LESSON 2-5
Solutions
1. 3 + 4 – 4 2. 7 + 9 – 7 = 3 + (4 – 4) = 9 + (7 – 7)= 3 + 0 = 9 + 0= 3 = 9
3. 8 – 2 + 2 4. 6 + 2 – 2 = 8 + (2 – 2) = 6 + (2 – 2)= 8 + 0 = 6 + 0= 8 = 6
2-5
Vocabulary and Concepts
Solving Equations by Adding or SubtractingPRE-ALGEBRA LESSON 2-5
Subtraction Property of Equality
You can subtract the same number from each side of an equation
Quick Check
2-5
Vocabulary
Arithmetic Algebra
10 = 2( 5 ) if a = b
10 – 5 = 2( 5 ) - _____ then a – c = b - _____c5
Solving Equations by Adding or SubtractingPRE-ALGEBRA LESSON 2-5
Addition Property of Equality
You can add the same number from each side of an equation
Quick Check
2-5
Vocabulary
Arithmetic Algebra
8 = 2( 4 ) if a = b
8 + 3 = 2( 4 ) + _____ then a + c = b + _____c3
____________________ are operations that undo each otherInverse Operations
Solve y + 5 = 13.
Solving Equations by Adding or SubtractingPRE-ALGEBRA LESSON 2-5
Method 1 Method 2y + 5 = 13 Subtract 5
y + 5 – 5 = 13 – 5 from each side.
y = 8 Simplify.
y + 5 = 13
y = 8
Check y + 5 = 13
8 + 5 13 Replace y with 8.
13 = 13
– 5 = – 5
Quick Check
2-5
Larissa wants to increase the number of books in her collection to 327 books. She has 250 books now. Find the number of books she needs to buy.
Solving Equations by Adding or SubtractingPRE-ALGEBRA LESSON 2-5
target numberWords plusis 250 number to buy
= number to buy.xLet
Equation 327 + x250=
2-5
(continued)
Solving Equations by Adding or SubtractingPRE-ALGEBRA LESSON 2-5
327 = 250 + x
Larissa needs to buy 77 more books.
327 = x + 250 Use the Commutative Property of Addition.
327 – 250 = x + 250 – 250 Subtract 250 from each side.
77 = x Simplify.
Check Is the answer reasonable?250 plus the number of books bought should be a total collection of 327.
250 + 77 = 327
2-5
Quick Check
Solve c – 23 = – 40.
Solving Equations by Adding or SubtractingPRE-ALGEBRA LESSON 2-5
c – 23 = – 40
c – 23 + 23 = – 40 + 23 Add 23 to each side.
c = –17 Simplify.
2-5
Quick Check
Marcy’s CD player cost $113 less than her DVD player. Her CD player cost $78. How much did her DVD player cost?
Solving Equations by Adding or SubtractingPRE-ALGEBRA LESSON 2-5
80 = t – 110
80 + 110 = t – 110 + 110 Add 110 to each side.
190 = t Simplify.
Marcy’s DVD player cost $190.
cost of CD player $113 cost of DVD playerWords less thanwas
t = cost of the DVD player.Let
t 110Equation 80 = –
2-5
Quick Check
Solving Equations by Adding or SubtractingPRE-ALGEBRA LESSON 2-5
Solve each equation.
1. y + 8 = 12 2. 7 + f – 21 = –20
3. 67 = g – (–36)
4. Ricky rides his bike 12 miles every day. He stops after 7 miles to rest. How much farther does he have to ride?
5 mi
4 –6
31
2-5