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SAT practise test 20000 part 8

Tham khảo tài liệu 'sat practise test 20000 part 8', ngoại ngữ, ngữ pháp tiếng anh phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 18. A Unpack the tangle of terms and you ll find the answer. You are looking for two prime numbers that 1. When you subtract them you get 21. 2. When you multiply them you get one of the answer choices. It might not sound like enough information to find the answer but it is. None of the answer choices are very great so one or both of the prime numbers must be less than ten. If the two primes were greater their product would not be as small as the answer choices. The difference between the two primes is 21 which means that one of the prime numbers must be small. Good candidates for the lesser prime are 2 3 or 5. Prime numbers starting in the 20s are 23 29 31 and 37. Use a little trial and error and you ll realize that the difference between 23 and 2 is 21. Those are the two primes. What is 2 times 23 The answer is 46 choice A . 19. B First it always helps to draw a quick sketch of the scenario to get a better grasp on what is being asked. The first thing to determine is the midpoint of DE which you can do by using the midpoint formula x11 x2 Y11 y2 0 15 121 0 5 12 _L 2D 5 Ự- 2D 5 S2 f D 5 2.5 6 You can keep the x-value as a fraction if you like but converting it to 2.5 will make it easier to punch into your calculator. Copyright 2005 Thomson Peterson s a part of The Thomson Corporaton 57 SAT is a registered trademark of the College Entrance Examination Board which was not involved in the production of and does not endorse this product. Looking at the dashed lines you can see a right triangle with its hypotenuse from the origin to the midpoint of DE. It has sides of 2.5 and 6. Placing those values into the Pythagorean theorem yields a2 1 b2 5 c2 2.52 1 62 5 c2 6.25 1 36 5 c2 42.25 5 c2 42.25 5 c 6.5 5 c It s choice B . 20. A It s a big equation but in the end it s just that an equation. You have to pull out two different techniques FOIL and PEMDAS to solve it but so long as you write out your work carefully you will reach the right answer. -b2 5 b - 7 b 1 3 - 2b 1 2