Algebra I All-in-One For Dummies. Mary Jane Sterling

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answer is positive. The answer is +4.

      Q.

      A. There are three negative signs in the problem, which is odd, so the answer is negative. The answer is –9.

      Q.

      A. There are two negative signs — one of them in front of the fraction — so the answer is positive. The answer is +11.

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Working with Nothing: Zero and Signed Numbers

      What role does 0 play in the signed-number show? What does 0 do to the signs of the answers? Well, when you’re doing addition or subtraction, what 0 does depends on where it is in the problem. When you multiply or divide, 0 tends to just wipe out the numbers and leave you with nothing.

Here are some general guidelines about 0:

       Adding zero: is just a. Zero doesn’t change the value of a. (This is also true for .)

       Subtracting zero: When doing subtraction with 0, order matters. Is 0 being subtracted or are you subtracting from 0?. When you subtract 0 from a number, you don’t change it.. Use the rule for subtracting signed numbers: Change the operation from subtraction to addition and change the sign of the second number, giving you .

       Multiplying by 0: . Twice nothing is nothing; three times nothing is nothing; multiply by nothing and you get nothing; likewise, .

       Dividing 0 by a number: . Take you and your friends: If none of you has anything, dividing that nothing into shares just means that each share has nothing.Note: You can’t use 0 as a divisor. Numbers can’t be divided by 0; not even 0 can be divided by 0. The answers just don’t exist.

      So, working with 0 isn’t too tricky. You follow normal addition and subtraction rules, and just keep in mind that multiplying and dividing with 0 (0 being divided) leaves you with nothing — literally.

      Q. Perform the operation:

      A. . Adding 0 to any number doesn’t change the number – even when the number is negative!

      Q. Perform the operations:

      A. 0. You want to pay attention to the whole problem. The first operations result in a huge number, but the final result is 0. That’s what 0 does best!

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Practice Questions Answers and Explanations

      1 4.6. The number 4.6 is to the right of 0 on the number line, and is to the left of 0. And, of course, a positive number will be larger than a negative number.

      2 0. Even though 0 isn’t positive (or negative), it’s to the right of , so 0 is larger.

      3 . To make the comparison easier, rewrite as , so it has the same number of decimal places as . The number is closer to 0 (on the left of 0), so it is larger.

      4 . The two negative numbers are the smallest, with the being farthest left and the smallest of the two. The number 4 is, of course, larger than 0.

      5 . The only positive number is , so it is largest. The number is closest to 0, so it’s the largest of the negative numbers. The number is the farthest from 0, so it’s the smallest.

      6 . The point of the inequality goes toward the smaller number.

      7 . The point of the inequality goes toward the smaller number, the .

      8 . The number is smaller than 11, so the point of the inequality points in that direction.

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