Quick combining terms clarification

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nortski

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Feb 27, 2020
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Hi guys, when combining negative like terms such as -3x -4x will give -7x. Does that mean that there's a hidden + between them?
 
nortski said:
Hi guys, when combining negative like terms such as -3x -4x will give -7x. Does that mean that there's a hidden + between them?
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Hidden? Well really it is maybe a short-cut: \(-3-4=(-1)(3+4)=(-1)(7)=-7\). Do you see the logic there?
 
nortski said:
Hi guys, when combining negative like terms such as -3x -4x will give -7x. Does that mean that there's a hidden + between them?
Click to expand...
A better way to think of it is that we define subtraction as addition of the opposite (negative): a - b means a + (-b).

So when we write -3x - 4x, that means (-3x) + (-4x). Not exactly "hidden", but implied. And often, seeing it in the latter way helps in carrying out the work.
 
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