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Simplify an Expression

Date: 6/15/96 at 19:50:0
Subject: Simplify an expression

Simplify  (9a + 2b) - (4a - 3b)

Date: 6/17/96 at 12:2:25
From: Doctor Dave
Subject: Re: Simplify an expression

Recall that a minus times a minus is a plus and a minus times 
a plus is a minus, so

 -(4a-3b) is the same as (-1)(4a-3b) 

and this is the same as (-1)(4a)+(-1)(-3b) 

which equals (-4a) + (3b)
So, (9a + 2b) - (4a-3b) = 9a + 2b - 4a + 3b 

If you combine like terms you get

9a - 4a + 2b + 3b = (9-4)a + (2+3)b = 5a + 5b

-Doctor Dave,  The Math Forum
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Associated Topics:
Middle School Algebra

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