美国高考ACT数学题.

�　　关于ACT数学同学们应该定期进行模拟练习，全面的考题使学生了解所有的题型分布，大量的练习为学生不断提高解题技巧和速度提供了保障。下面我们来看一下美国高考ACT数学题。

　　1. 3x3�2x2y�4x2y is equivalent to:

　　A. 9x7y2

　　B. 9x12y2

　　C. 24x7y2

　　D. 24x12y

　　E. 24x12y2

　　解析：The correct answer is C. To find an equivalent expression, you can multiply the constants (3�2�4), combine the x term (x3x2x2 → x3+2+2 → x7, because when you have a common base you use the base and add the exponents), and combine the y terms (y�y → y1y1 → y1+1 → y2). The result is 24x7y2.

　　正确答案选C。常数相乘(3�2�4)，合并x项(x3x2x2 → x3+2+2 → x7) 和y项(y�y → y1y1 → y1+1→ y2)，结果为24x7y2。

　　2. Mr. Dietz is a teacher whose salary is $22,570 for this school year, which has 185 days. In Mr. Dietz&apos&aposs school district, substitute teachers are paid $80 per day. If Mr. Dietz&apos&aposs takes a day off without pay and a substitute teacher is paid to teach Mr. Dietz&apos&aposs classes, how much less does the school district pay in salary by paying a substitute teacher instead of paying Mr. Dietz&apos&aposs for that day?

　　F. $ 42

　　G. $ 80

　　H. $ 97

　　J. $105

　　K. $122

　　解析：The correct answer is F. To find Mr. Dietz&apos&aposs pay per day, you can divide his salary, $22,570, by the number of days he works,185. His pay per day is 22570/185, or $122. When Mr. Dietz takes a day off without pay and the school pays a subsititute $80, the school district saves the difference in these amounts, 122-80, or $42.

　　正确答案选F。先算出Dietz先生每天的平均工资，用22570除以185(可用计算器)，即122美元。再用122美元减去学校需要支付临时老师的费用80美元，即可算出学校结余的费用，为42美元。

　　3. So far, a student has earned the following scores on four 100-point tests this grading period:65,73,81, and 82. What score must the student earn on the fifth and last 100-point test of the grading period to earn an average test grade of 80 for the 5 tests?

　　A. 75

　　B. 76

　　C. 78

　　D. 99

　　E. The student cannot earn an average of 80.

　　解析：The correct answer is D. To find what the student needs to score on the fifth 100-point test to average a score of 80, you need to find the point total for the student so far by adding 65,73, 81 and 82. That sum is 301. Averaging 80 points on 5 tests means the student must earn 400 points (80�5). The acore needed on the last test is the difference,400～301, or 99.

　　正确答案选D。该学生前四次共得301分;5次考试平均分为80，意味着5次考试总分需达到400分，那么该学生最后一次考试需要达到的分数为400与301的差，即99分。

　　4. A rectangular lot that measures 150 ft by 200 ft is completely fenced. What is the approximate length, in feet, of the fence?

　　F. 300

　　G. 350

　　H. 400

　　J. 700

　　K. 1,400

　　解析：The correct answer is J. To find the length of fence needed to fence a rectangular lot 150 ft by 200 ft, you need to find the perimeter. The formula for the perimeter of a rectangle is 2 times the sum of the length and width, or P = 2( l+ w). 2(150 +200) =2(350) =700.

　　正确答案选J。所需篱笆的长度即为这块长150英尺宽200英尺矩形土地的周长。根据矩形周长公式，可知：矩形周长=2(长+宽)，即2(150 +200) =2(350) =700英尺。

　　5. The expression a[b+(c-d)] is equivalent to:

　　A. ab + ac - ad

　　B. ab + ac + ad

　　C. ab + ac - d

　　D. ab + c + d

　　E. ab + c - d

　　解析：The correct answer is A. To find an equivalent expression, multiply a by b+c-d. This results in a(b) + a(c) + a(-d), or ab + ac - ad.

　　正确答案选A。根据乘法分配率展开括号可得ab + ac - ad。

　　以上就是美国高考ACT数学题的详细内容，非常实用。要想ACT数学成绩有所提高，坚持每天做练习是十分必要的，就像这样每天完成ACT数学题，并进行总结，日积月累，成绩就会有明显地提高。