Question 773737: Is this how to reduce this expression?
5a-{-[(-3a+2b)-4b]+[-7a-(a-b)]-3b}
=5a-{-[-3a+2b-4b]+[-7a-a+b]-3b}
=5a-{3a-2b+4b+7a+a-b-3b}
=5a-3a+2b-4b-7a-a+b+3b
=-6a+2b
Answer by KMST(5328)   (Show Source):
You can put this solution on YOUR website! 5a-{-[(-3a+2b)-4b]+[-7a-(a-b)]-3b}
=5a-{-[-3a+2b-4b]+[-7a-a+b]-3b} (now you can collect like terms)
=5a-{-[-3a-2b]+[-8a+b]-3b}
=5a-{3a+2b-8a+b-3b} (now you can collect like terms again)
=5a-(-5a)
=5a+5a
=10a
The mistake:
=5a-{-[-3a+2b-4b]+[-7a-a+b]-3b}
=5a-{3a-2b+4b-7a-a+b-3b} (when you remove a set of parentheses that follow a + sign, you leave all the signs that wewere inside the parentheses as they were before.
Also, collecting like terms when you have a chance makes the expression shorter and simpler. That reduces the risk of accidentally forgetting a term. Maybe you do not make that kind of mistakes, but I often do, so I prefer to somplify as often as I can.
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