a+b=m , a-b=?

Dec 2015
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Earth
If \(\displaystyle a+b=m\) , express \(\displaystyle a-b\) in terms of m .
\(\displaystyle a-b=f(m)=\)?
 
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May 2013
100
10
so lets take some examples and see if we can figure out a rule.
2+3 = 5
2-3 = -1
4+2 = 6
4 -2 = 2
7 +11 = 18
7 - 11 = -4
so it looks like our rule is:
if a +b = m
a -b = m -2b
 

mathman

Forum Staff
May 2007
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If \(\displaystyle a+b=m\) , express \(\displaystyle a-b\) in terms of m .
\(\displaystyle a-b=f(m)=?
\)
Doubtful. Example: m=0, then a+b=0. As a result let a=x thus b=-x so a-b=2x, where x can be any number. So f(m)=2x, not at all defined.
 
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topsquark

Math Team
May 2013
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The Astral plane
If \(\displaystyle a+b=m\) , express \(\displaystyle a-b\) in terms of m .
\(\displaystyle a-b=f(m)=\)?
Or, in symbols:
a + b = m
a - b = a + (b - 2b) = (a + b) - 2b = m - 2b

-Dan
 
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