※ 引述《haby (haby)》之铭言： : 20.If -2x > 3y, is x negative? : (1) y > 0 : (2) 2x + 5y - 20 = 0 : 答案D 比较困惑第二个答案要怎麽推得呢?? 原题 0>2x+3y (2) 2x+5y=20 但 2x+3y<0 把(2)看成(2x+3y)+2y=20 知y>0 带回原题 x<0 : 21.Is the integer n odd? : (1) n is divisible by 3. : (2) 2n is divisible by twice as many positive integers as n. : 答案B (不太懂第二个选项的意思) (2)的意思是说 2n可以整除的正整数是n的两倍 n=9 则有 1.3.9 则2n就是*6 n=8 1.2.4.8 2n=1.2.4.8.16 这是因为奇数时 因数也会奇树 乘以2 两者没有公因数 所以变成交叉相乘2*3个奇因数 : 168. : In a certain senior class, 72 percent of the male students and 80 percent of : the female students have applied to college. What fraction of the students in : the senior class are male? : (1) There are 840 students in the senior class. : (2) 75 percent of the students in the senior class have applied to college. : 答案B 我选C @@~~ students=f+m (1) 只知f+m=840 (原题则是说72%的m和80%的f) (2) 75%(f+m) 有申请学校 75%(f+m)=72%m+80%f ꔳ3%m=5%f 3m=5f 괠原题要求的是m/f+m 的比例 选b : 214. : Is the measure of one of the interior angles of quadrilateral ABCD equal to : 60 degrees? : (1) Two of the interior angles of ABCD are right angles. : (2) The degree measure of angle ABC is twice the degree measure of angle BCD. : 答案E : 希望有好心的大牛解答喔^^ (1) 用直角梯型看 不一定 (2) 只知道b是c的两倍还是不能确定有一角会等於60 选e --

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