负数英文

Negative numbersRecognising negative numbersYou have to be able to use negative (or directed) numbers in many everyday contexts, for example with temperatures, bank balances etc.A temperature of 6 degrees below zero is −6°.If your bank account is £100 overdrawn, then your balance is −£100.In your exam, you might be asked to put some numbers in order. You have to remember, for instance, that −10 is less than −5.Sometimes it helps to see negative numbers on a number line. Try the question below:QuestionOrder the numbers - 5, −2, 3, −9, −2.5, 0.5.Negative numbers and temperatureYou need to be able to work out rises and falls in temperature usingnegative numbers.A number line can help us to understand changes in temperature. For example, if the overnight temperature fell to −4°C, and bymidday it had risen to 7°C, then, counting from −4 up to 7 on the number line,the temperature has gone up by 11°C.QuestionAt 6pm, the temperature was 3°C. By midnight, it had dropped to −5°C. How great was the fall in temperature?AnswerDid you get 8°C?If so, well done. You counted down 3, then another 5, to get 8.If you had problems, look at the number line.Counting down from 3 to -5 on the number line, we get 8 degrees. Here is a different question:QuestionAt 7am, Joe recorded the temperature in his garden as being −4°C. He went back outside at 1pm and found that the temperature hadincreased by 12°C. What was the temperature at 1pm?AnswerThe temperature at 1pm was 8°C.Starting at −4 and counting up 12, we get to 8.Try this one:QuestionAt 6pm, the outside temperature was 7°C. By 6am, the temperature had dropped by 13°C. What was the temperature at 6am?AnswerDid you get the answer −6°C?If so, well done. You counted down 13 from 7.If you had problems, look at the number line:Starting at 7 and counting down by 13 on the number line, we get to −6. So the temperature at 6am was -6°C.Here is a table showing temperatures in cities worldwide:insert caption hereCity TempAlgiers 16°CBarcelona 17°CLondon 5°CNew York 7°CMoscow −9°COslo −5°CParis 12°CSydney 23°CYou could be asked to find the difference in temperature between two cities, eg, Moscow and London.Moscow is −9°C. London is 5°C.Starting at −9, we count up 14 to get to 5. So the difference in temperatures is 14°C.Try this question:QuestionWhat is the difference in temperature between Moscow and Oslo? Simple negative number arithmeticTo do algebra (especially graphs), you will need to know some basic facts about adding, subtracting, multiplying and dividing with negative numbers.Here are the basic rules for adding and subtracting:Adding a negative number is the same as subtracting:eg 7 + (−3) is the same as 7 − 3 = 4Subtracting a negative number is the same as adding:eg (−5) − (−2) is the same as (−5) + 2 = −3Try these two:Question4 − (−3)AnswerDid you get 7? If you had problems, remember that 4 − (−3) is the same as 4 + 3 = 7Question5 + (−8)AnswerThe answer is -3.If you had problems, remember that 5 + (-8) is the same as 5 − 8 = −3Here are the rules for multiplying and dividing:MultiplicationPositive × positive = positivePositive × negative = negativeNegative × positive = negativeNegative × negative = positiveIf the signs are the same, the answer is positive. If the signs are different, the answer is negative.Here are some examples:−4 × 2 = −8−3 ×−2 = 65 ×−3 = −15Now you try these questions:Question−10 ×−3AnswerDid you get 30? Remember that negative × negative = positive. DivisionDivision follows the same rules as multiplication. So, for example, −24 ÷ 6 = −4, because 24 ÷ 6 = 4 and the answer must be negative. Try this question:Question-7 × 3AnswerDid you get −21? Remember that negative × positive = negative. Question-21 ÷ 3负数--测试Negative numbers - Test姓名nameCities worldwide TempAlgiers 16°CBarcelona 17°CBerlin 8°CLondon 5°CMoscow -9°CNew York 7°COslo -5°CParis12°CRome 15°CSydney 23°C5.What was the difference in temperature between Barcelona and Berlin?°C6.How much higher was the temperature in Rome than the temperature in Oslo?°C7.5 + (-7) =8.17 - (-8) =9.(-6) x (-3) =10.50 ÷ (-10) =Write the following as directed numbers.1.40 metres below sea level. m2.A temperature of 8 degrees below zero. °CUse the number line to help you to answer the following questions.3.At 9pm, the temperature was 2°C. By midnight, the temperature had dropped to -5°C. By how many degrees had the temperature fallen?°C4.The temperature at midnight was -3°C. By 8am, it had risen by 6°C. What was the temperature at 8am?°C。