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 Posted: Mon Aug 13, 2007 1:48 pm
can someone explain to me how to add and subtract fractions
yea i know its simple but...i cant remember *is having a blonde moment*
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Posted: Mon Aug 13, 2007 1:50 pm
and if someone could re-explain negatives and how to use them (add subtract multiply divide rules)
that would be great
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Posted: Sat Aug 25, 2007 4:53 pm
Better late than never.
Adding/Subtracting Fractions
So you want to solve the following problem:
a/b + c/d = ?
Where a, b, c, and d are generic integers.
1. Find a common multiple of b and d. Most teachers tell you to find the least common multiple for simplicity, but if you're lazy you can just multiply b x d. We'll call this multiple m.
2. Figure out what you have to multiply b by to get m. Multiply both the top and the bottom of a/b by this number so that the fraction looks different, but the value doesn't change. Do the same for the second fraction.
You should now have something that looks like e/m + f/m = ?
3. Add the top row. Put m on the bottom: g/m.
4. Simplify the fraction so it is in lowest terms.
***
Negatives
Multiplication and Division:
1. Forget about the signs. Multiply the numbers.
2. Count the number of negative signs. If it's 0 or even, your answer is positive. If it's odd, your answer is negative.
Addition:
1. If two numbers are the same sign, add the two numbers and keep the same sign.
2. If the two numbers have different signs, drop the signs and subtract the smaller number from the bigger one. Throw the bigger number's sign on the answer.
Subtraction:
Change it into an addition problem.
Ex: 5 - 7 = 5 + -7
-4 - (-9) = -4 + 9.
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