addition equations
TRANSCRIPT
Course 1
2-5 Addition Equations
Course 1
2-5 Addition Equations
Course 1
Warm UpWarm Up
Lesson PresentationLesson Presentation
Problem of the DayProblem of the Day
Course 1
2-5 Addition Equations
Warm UpDetermine whether each value is a solution.
1. 86 + x = 102 for x = 16
2. 18 + x = 26 for x = 4
3. x + 46 = 214 for x = 168
4. 9 + x = 35 for x = 26
yes
no
yes
yes
Course 1
2-5 Addition Equations
Problem of the Day
After Renee used 40 m of string for her kite and gave 5 m to her sister for her wagon, she had 8 m of string left. How much string did she have to start with?53 m
Course 1
2-5 Addition Equations
Learn to solve whole-number addition equations.
Course 1
2-5 Addition Equations
The equation h + 14 = 82 can be represented as a balanced scale.
h + 14 82
To find the value of h, you need h by itself on one side of the scale.
h ?
To get h by itself, first take away 14 from the left side of the scale. Now the scale is unbalanced.
h 68To rebalance the scale, take away 14 from the other side.
h + 14 82
Course 1
2-5 Addition Equations
Taking away 14 from both sides of the scale is the same as subtracting 14 from both sides of the equation.
h + 14 = 82–14 –14h = 68
Subtraction is the inverse, or opposite, of addition. If an equation contains addition, solve it by subtracting from both sides to “undo” the addition.
Course 1
2-5 Addition Equations
Solve the equation. Check your answer.
Additional Example 1A: Solving Addition Equations
x + 87 = 152
Check x + 87 = 152
x + 87 = 152 87 is added to x.
x = 65
– 87 – 87 Subtract 87 from both sides to undo the addition.
65 + 87 = 152?
152 = 152?
Substitute 65 for x in the equation.
65 is the solution.
Course 1
2-5 Addition Equations
Solve the equation. Check your answer.
Additional Example 1B: Solving Addition Equations
72 = 18 + y
Check 72 = 18 + y
72 = 18 + y 18 is added to y.
54 = y
–18 –18 Subtract 18 from both sides to undo the addition.
72 = 18 + 54?
72 = 72?
Substitute 54 for y in the equation.
54 is the solution.
Course 1
2-5 Addition Equations
Solve the equation. Check your answer.
Check It Out: Example 1A
u + 43 = 78
Check u + 43 = 78
u + 43 = 78 43 is added to u.
u = 35
– 43 – 43 Subtract 43 from both sides to undo the addition.
35 + 43 = 78?
78 = 78?
Substitute 35 for u in the equation.
35 is the solution.
Course 1
2-5 Addition Equations
Solve the equation. Check your answer.
Check It Out: Example 1B
68 = 24 + g
Check 68 = 24 + g
68 = 24 + g 24 is added to g.
44 = g
–24 –24 Subtract 24 from both sides to undo the addition.
68 = 24 + 44?
68 = 68?
Substitute 44 for g in the equation.
44 is the solution.
Course 1
2-5 Addition Equations
Johnstown, Cooperstown, and Springfield are located in that order in a straight line along a highway. It is 12 miles from Johnstown to Cooperstown and 95 miles from Johnstown to Springfield. Find the distance d between Cooperstown and Springfield.
Additional Example 2: Social Studies Application
It is 83 miles from Cooperstown to Springfield.
95 = 12 + d
distance between Johnstown and Springfield
distance between Johnstown and Cooperstown
distance between Cooperstown and Springfield
= +
95 = 12 + d
–12 –12
83 = d
12 is added to d.
Subtract 12 from both sides to undo the addition.
Course 1
2-5 Addition Equations
Patterson, Jacobsville, and East Valley are located in that order in a straight line along a highway. It is 17 miles from Patterson to Jacobsville and 35 miles from Patterson to East Valley. Find the distance d between Jacobsville and East Valley.
Check It Out: Example 2
It is 18 miles from Jacobsville to East Valley.
35 = 17 + d
distance between Patterson and East Valley
distance between Patterson and Jacobsville
distance between Jacobsville and East Valley
= +
35 = 17 + d
–17 –17
18 = d
17 is added to d.
Subtract 17 from both sides to undo the addition.
Course 1
2-5 Addition Equations
Solve each equation.
1. x + 15 = 72
2. 81 = x + 24
3. x + 22 = 67
4. 93 = x + 14
Lesson Quiz
x = 57
x = 57
x = 45
x = 79
56 inches
5. Kaitlin is 2 inches taller than Reba. Reba is 54 inches tall. How tall is Kaitlin?