s clear the brackets. Then clear the parentheses in that order. Superscript(1) factor is a value, a symbol that we multiply by. To factor an expression is to break the expression up into components and when these components are multiplied together, we derive the original expression. For example, 12 and 5 are factors of 60 because 12 X 5 = 60. A REVIEW OF MATHEMATICS FOR TELECOMMUNICATION APPLICATIONS Example. Simplify: (r - 3R) - [(2R - r) + 1] = (r - 3R) - (2R - r) - 1 - 3R - 2R + r - 1 = 2r - 5R - - 1. Fractions. We review the adding and subtracting of fractions in arithmetic. Add: 3/4 + 5/8 + 5/12. Remember that we look for the least common denominator (LCD). In this case it is 24. The reason: 24 is divisible by 4, 8, and 12. The three terms are now converted to 24ths or: 18/24 + 15/24 + 10/24 Now add 18, 15, and 10, which is 43/24 or 1 + 19/24. Another example: Add 1/6 + 1/7 + 1/8. The best we can do here for the LCD is the product of the three denominators 6 X 7 = 336, then convert to 336's or 56/336 + 48/336 + 42/336. Now add derived numerators or 56 + 48 + 42 = 146. Our new fraction after addition is 146/336. Divide numerator and denominator by 2 and the answer is 73/168. Subtraction of fractions follows the same procedure, just follow the rules of signs. Example. Calculate 1/4 - 1/5 + 2/3. Procedure. Multiply the denominators together for the LCD, the value is 60. Convert each fraction to 60ths or 15/60 - 12/60 + 40/60. We now have a common denominator SO we can add the numerators: 15 - 12 + 40 = 43/60. We apply the same procedure when we add/subtract algebraic symbols. Example. Simplify 1/(X - 4) - 1/(X- Procedure. The LCD is the product (X - 4)(X - 5). We then have [(X - 5) - (X - 4) ((X -4)(X - 5) = -1/(X2 -9X + 20). Then multiply the two factors (X - 4) and (X - 5). There are two approaches. Do "long" multiplication as we would do with arithmetic: X - 4 5X + 20 X2 4X sum X2-9X+20 The second approach: (X - 4) X (X - 5). Multiply the leftmost terms (the Xs) and we get X2; multiply the right sides (-4 an