Question 29276: I am helping my son with pre alegebra, his book is ridiculous for examples: These are what I need help on.
1. Simplify: -(-{-[-(2)]}), 2. Simplify (4)(-3), 3. Simplify: (-3)(-3)(-3)(-3). Evaluatexy-y, if x=6 and y=-5, evaluate -ab-a, if a=-4 and b=-5.
Answer by longjonsilver(2297)   (Show Source):
You can put this solution on YOUR website! 1. -(-{-[-(2)]})
rather pointless question, but anyway :-)... what this means is the following:
-1*(-1*{-1}). As to how we work it out...we start at the inner most brackets and work outwards,
so... -1*2...meaning -1*+2 is -2, so:
-1*(-1*{-1*(-2)})
-1*(-2) is? +2, so
-1*(-1*{2})
And -1*{2} is? answer is -2. So,
-1*(-2)
and finally, -1*(-2) is +2
so answer is +2.
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2. (4)(-3)?
this means (+4)*(-3)
+ and - make a -
4 and 3 are 12
--> answer is -12
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3. (-3)(-3)(-3)(-3) means
(-3)*(-3)*(-3)*(-3)
so, take it in bits:
first 2 terms are: (-3)*(-3) is +9
last two terms are the same
So we have 9*9 --> +81
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if x=6, y=-5
xy-y is
(6)(-5)-(-5) meaning
(+6)*(-5)-(-5)
So, (+6)*(-5) is -30, so we have -30-(-5)
we can also think of -(-5) as -1*(-5) --> +5, so we get -30+5 which is -25
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-ab-a
-(-4)(-5)-(-4)
you try this one... answer is -16
jon.
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