2 8 UNDOING OPERATIONS Pages 144 150 WARMUP
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2. 8 – UNDOING OPERATIONS Pages 144 - 150
WARMUP Please write the “Number Trick” in words and in math language, one step at a time. Give your answer at the end. • Pick a number and then do the following operations in order: Add 3, multiply by 7, subtract 4, divide by 2, and add 1.
I BET I CAN GUESS YOUR STARTING NUMBER. Do you think that if you told somebody your final answer, they can guess your starting number? Tell Mr. Schaner your final answer and see if he can guess your starting number. Learning Target: � In Investigation 2. 8: Just Undo It!, we will figure out how to find anyone’s starting number if they go through the steps (correctly) of the “number trick. ”
INVESTIGATION 2. 8: JUST UNDO IT! Description Pick a number Sequence ? Expression Undo Result 44 Divide by 4 Answer / 4 11 Add 7 Answer + 4 18 Multiply by 2 36 Subtract 8 28 Now let’s set this equation equal to 28 and solve for x.
PARTNER WORK: DO THIS PROBLEM WITH YOUR PARTNER Solve the following by “undoing” the operations. � � We start at x and work our way out to write the description The number of rows needed = number of operations +1 Equation: Expression Description Undo (Do the opposite) Result
DID I GET THAT? – 2. 8 Using a table, find out what x is? Equation: Expression Description Undo (Do the Opposite) Result 42
