Solving Two-Step Equations Find the Error

What is the first step in solving the equation 2a - 4(a - 5) = 10

• Add 4 to both sides

• Add the 2a and a 

• Distribute 4 to a and -5

• Distribute -4 to a and -5

Using the "opposite operation" to "undo" and isolate the variable when solving an equation is more commonly called...

• Inverse operations

• math

• variable

• PEMDAS

What is the first step to complete when solving this equation?
10 - 3x = 4

• Subtract 10

• Add 10

• Add 3

• Divide by -3

• A
• B
• C
• D

• A
• B
• C
• D

What is the error?

• Adding 2x to 3x

• Subtracting 5 from both sides

• Adding 2x to -2x

• Dividing by 5 on both sides

Solve the two step equation above.

(type your whole solution with the variable and the equal sign)

Mathematical Equivalence

ON

Find the Error
What error did the student make when solving the equation:
1/5x + 6 = 3/5x + 5
1x + 6 = 3x + 5
-2x + 6 = 5
-2x = -1
x = 1/2

• The student found an incorrect common denominator

• The student did not multiply all terms by the common denominator

• The student did not use opposite operations appropriately

• The student did not correctly eliminate the variable from one side of the equation

Find the Error
What error did the student make when solving the equation:
5x + 6 =  66
5x - 6 = 66 -6
5x = 60
5*5x= 60*5
x = 300

• The student subtracted 6 from both sides instead of adding

• Student multiplied by 5 instead of dividing by 5

• Student got the wrong answer when subtracting 66-6

• The student did not correctly eliminate the variable from one side of the equation

The goal of solving a one, two, or multi-step equations is to:

• Find the constant

• Find the coefficient

• Find the value of the variable

• Guess and check