If the x in x(22-19) is tripled, how much will the expression change?
I’m helping my brother study for an exam and the book asks, If x in x(22-19) is tripled, how much is the value of the expression changed? I’m so sure it should be “three times,” but the answer says 6 times. It gives the explanation that you subtract x(22-19) from 3x(22-19) and then get 6x. This works, but when I...
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answers:
L. E. Gant say: x (22-19) = 3x This is the "old" value
3x(22-19) = 9x This is the "new" value

It's a matter of the wording:
The new value has changed to 3 times the old value (which is what you are taking as the answer).
However the amount the expression has changed is the difference between the new value and the old value (which is what the books says). or...
9x - 3x = 6x

Testing:
if x = 2 then the old value is 2 * 3 = 6;
Then the new value is 6 * 3 = 18
but the difference is 18 - 6 = 12 = 6 * 2 ( 6 times the old value of x)
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Morningfox say: Yes, the expression will be three times larger. But that is also equal to original value PLUS 6x.
(original value) times (3) = (original value) plus (6 times original value).
Try it with x = 1 (for example).
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brainyandy say: Not sure if I can help you on this one but unless there’s something that I don’t know about then the answer is simply 3x(22-19). The other way of looking at it is that 22-19 = 3 so the original equation is 3x. Tripling this of course give 9x.
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Charles D say: This looks like a trick question. It looks like they are using the word "expression" to mean "x".
So if x is multiplied by 2 (that is 22-19) and then tripled, 3. x is changed by 6.

No one would read it this way. As much as you might think that your knowledge is being tested, what you (your brother is) doing is passing a test. If you see this question on the test the answer is "6".

Keep doing the practice problems. If it is a good test book, you will see many of them on the test.

Good luck.
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billrussell42 say: not sure what you mean by x(22-19)
because that is just 3x from the elementary rules of math.

and if you triple it you get 9x

perhaps if you told us the "original problem" ??
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