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6x-13+4(-3)x=9+2x

I'm like, really dumb, I can't tell if if the 4(-3) bit is a multiplication

Delta
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  • @Delta : there's no other meaning that makes sense. Where did this come from? – Stefan Smith Nov 20 '13 at 23:50
  • @StefanSmith Oh, it's been a while since I don't study any math, so I was going through all the basic stuff all over again and ran into this stupidity of mine while reading this http://www.wikihow.com/Isolate-a-Variable – Delta Nov 21 '13 at 00:05

3 Answers3

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Yes, it is multiplication that's implied. It's called "juxtaposition", where factors in a product abut each other. Unless otherwise specified, we take the operation to be multiplication. $$a(b)c = abc = a\times b\times c$$

amWhy
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Yes, it is a multiplication. In mathematical notation, we often just leave out multiplication signs when they are implied.

Newb
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$6x-13+4(-3)x=9+2x$

is the same as the equation $6*x-13+4*(-3)*x=9+2*x$

which is the same as $(6*x)-13+(4*(-3)*x)=9+(2*x)$

which is the same as $(6*x)-13+((-12)*x)=9+(2*x)$

which is the same as $(6*x)-13-(12*x)=9+(2*x)$

What happens is something similar to what happens when you add an x into the equation. Just like $6x$ is the same as $6*x$ the same happens with parenthesis. so $4(3)$ is the same as $4*3$

Asinomás
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