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Math Question

Math Question

Posers and Puzzles

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I know this is not the place to ask math questions, but since Im doing an online math class, Its hard for me to ask a real person.

In my Math textbook, Im having a hard time understanding this problem, I know its something simple, I just cant figure out what. The fact that Im dum at math isnt helping any.

Simplify: -2(x-5)+ 4(2x + 2)


This is how the book says to simplify.
-2(x-5)+ 4(2x + 2) = -2*x + (-2)(-5) + 4*2x + 4/2
= -2x + 10 + 8x +8
= 6x + 18


This is how it seems to me it should go, which gives it a totaly different answer.
-2(x-5)+ 4(2x + 2) = -2*x -(-2)(-5) + 4*2x + 4/2
= -2x - 10 + 8x +8
= -2x + (-10) + 8x +8
= 6x + (-2) or = 6x - 2

So what am I doing wrong? Why are they changing the minus sign to a plus sign when they are caculating, for no reason at all?

* = mutiply

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Originally posted by flyUnity
This is how it seems to me it should go, which gives it a totaly different answer.
-2(x-5)+ 4(2x + 2) = -2*x -(-2)(-5) + 4*2x + 4/2
= -2x - 10 + 8x +8
= -2x + (-10) + 8x +8
= 6x + (-2) or = 6x - 2

So what am I doing wrong? Why are they changing the minus sign to a plus sign when they are caculating, for no reason at all?

* = mutiply
your problem is in the first distribution. The -2 needs to go to the x, which you did right, but also to the -5, and (-2)*(-5) is (+10).

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Originally posted by Coconut
your problem is in the first distribution. The -2 needs to go to the x, which you did right, but also to the -5, and (-2)*(-5) is (+10).
Ok, I got it now, I dont know what I was thinking. Thanks 🙂

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Originally posted by flyUnity
Ok, I got it now, I dont know what I was thinking. Thanks 🙂
Hope you are never plotting a course for a plane I'm on.

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Originally posted by XanthosNZ
Hope you are never plotting a course for a plane I'm on.
Dont worry, Computers plot my courses now. They give me headings, bearings, relative winds, and magnetic error variations all with with only pressing a few buttons on the computer. 😛

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Originally posted by flyUnity
Dont worry, Computers plot my courses now. They give me headings, bearings, relative winds, and magnetic error variations all with with only pressing a few buttons on the computer. 😛
i hope the buttons are not plus or minus buttons lols

thanks for the laugh

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Originally posted by flyUnity
Dont worry, Computers plot my courses now. They give me headings, bearings, relative winds, and magnetic error variations all with with only pressing a few buttons on the computer. 😛
press a wrong button, how do you know you're not flying off into oblivion?

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Hey, Im not that dumb. Flying is easier then driving a car.

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Originally posted by flyUnity
Hey, Im not that dumb. Flying is easier then driving a car.
Especially if you are in a plane.

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I learnt that a minus times a minus is a plus when I was four months old.

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Originally posted by Bowmann
I learnt that a minus times a minus is a plus when I was four months old.
Slow learner.

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Originally posted by flyUnity
Hey, Im not that dumb. Flying is easier then driving a car.
Umm...are you telling us it's ok that you're a pilot even though driving is too difficult for you?

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Originally posted by Gastel
Slow learner.
I was busy studying philosophy.

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Originally posted by Bowmann
I was busy studying philosophy.
"studying"? "philosophy"? oxymoron?