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5 votes
When aaliyah picks any number between 1 and 20, doubles it,adds 6,divide by 2 and subtract 3, she always gets the number she started with. evaluate and use algebraic evidence to support your conclusion.

User EZI
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2 Answers

7 votes
Lets say x is a number that is 1-20. The equation is

(((x * 2) + 6) / 2) - 3 = x
We then work backwards, add 3

((x * 2) + 6) / 2 = x + 3
The multiply by 2

(x * 2) + 6 = 2(x + 3)
Then simplify

2x + 6 = 2x + 6
As you can see, they are equal to each other and can further condense it, making it into

x = x
User Sayil Aguirre
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6.4k points
2 votes
Any number between 1 and 20. Let's choose 3 different numbers. I choose 11, 16, and 6.

(16 + 16 + 6)/2 - 3 = 16
(11 + 11 + 6)/2 - 3 = 11
(6 + 6 + 6)/2 - 3 = 6

It seems Aaliyah is correct. We can she she's using this equation to come up with this "trick."

Evaluation:
(2x + 6) / 2 - 3
= 2(x+3) / 2 - 3
= x + 3 - 3
= x

User Joshua Miller
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5.8k points