tailieunhanh - Sat - MC Grawhill part 29

Tham khảo tài liệu 'sat - mc grawhill part 29', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 270 McGRAW-HILL S SAT Lesson I Numbers and Operations Integers and Real Numbers On the SAT you only need to deal with two kinds of numbers integers the positive and negative whole numbers . . . 3 2 1 0 1 2 3 . . . and real numbers all the numbers on the number line including integers but also including all fractions and decimals . You don t have to know about wacky numbers such as irrationals or imaginaries. Using inverse operations helps you to solve equations. For example 3x - 7 38 To undo 7 add 7 to both sides 3x 45 To undo X 3 divide both sides by 3 x 15 The SAT only uses real numbers. It will never 1 divide a number by 0 or 2 take the square root of a negative number because both these operations fail to produce a real number. Make sure that you understand why both these operations are said to be undefined. Don t assume that a number in an SAT problem is an integer unless you are specifically told that it is. For instance if a question mentions the fact that x 3 don t automatically assume that x is 4 or greater. If the problem doesn t say that x must be an integer then x might be or or the like. Alternative Ways to Do Operations Every operation can be done in two ways and one way is almost always easier than the other. For instance subtracting a number is the same thing as adding the opposite number. So subtracting 5 is the same as adding 5. Also dividing by a number is exactly the same thing as multiplying by its reciprocal. So dividing by 2 3 is the same as multiplying by 3 2. When doing arithmetic always think about your options and do the operation that is easier For instance if you are asked to do 45 1 2 you should realize that it is the same as 45 X 2 which is easier to do in your head. The Operations The only operations you will have to use on the SAT are the basics adding subtracting multiplying dividing raising to powers and taking roots. Don t worry about bad boys such as sines tangents or logarithms they won t show up. Yay Don t confuse the