Download Lesson 1-12a

1-12
6th grade math
Solving Addition and Subtraction
Equations
Objective
• To solve one-step linear equations in one
variable.
• Why? To master another aspect of Algebra
and Functions in 6th grade math (and beyond).
Being able to solve equation is a key
component in Algebra and other higher math.
California State Standards
AF 1.1 : Write and solve one-step linear
equations in one variable
MR 3.3: Develop generalizations of the results
obtained and the strategies used and apply them
in new problem situations.
Vocabulary
• Expression
- A mathematical phrase made up of a combination of variables and/or
numbers and operations. Expression with variables are also called algebraic
expressions. Expressions with variables must have a number to substitute
the variable and then solve.
• 5n, n = 4. 5 x 4 = 20; 4x – 7; (5 x 2) – 6/3; …
• Equation
– A number sentence stating that two expressions are equal. Solving
equations is like balancing a scale. Of you add or subtract a number to
one side, you must also add or subtract that number to the other side in
order to maintain the equality (or balance). Your goal is to ‘isolate the
variable’ on one side of they equation.
• 3 + 5 = x; 8x = 32; …
• Inverse Operations
– Two operations with an opposite effect. Addition and subtraction are
inverse operations. Multiplication and division are inverse operations.
Inverse operations ‘undo’ each other. You solve equations by using
inverse operations.
How to Solve Equations with
Addition or Subtraction
1) Read the equation and
understand what you
need to do to ISOLATE
THE VARIABLE.
2) First undo the
subtraction to BOTH
sides.
3) Carefully solve and
check your work by
substituting the solved
number into the
equation.
A) x – 26 = 85
x - 26 + 26 = 85 + 26
x = 111
B) w + 41.8 = 55.9
w + 41.8 – 41.8 = 55.9 – 41.8
w = 14.1
C) 0.6 = p + 0.5
0.6 – 0.5 = p + 0.5 – 0.5
0.1 = p
Try It!
Solve each equation.
1) 26
1) a + 17 = 43
2) 88
2) x – 22 = 66
3) 138 + g = 150
4) y + 8.3 = 9.2
3) 12
4) 0.9
Objective Review
• You can now solve one-step linear
equations in one variable.
• Why? You have now mastered another aspect of
Algebra and Functions in 6th grade math (and beyond).
Being able to solve equation is a key component in
Algebra and other higher math. You can solve addition
and subtraction equations by adding or subtracting the
same amount on both sides of the equations.
REMEMBER TO ISOLATE THE VARIABLE!
Independent Practice
• Complete problems 617, 19.
• Copy original problem
first.
• Show all work!
• If time, complete Mixed
Review: 20-28.
• If still more time, work
on Accelerated Math.