ReviewQuestionsofAlgebra
2011-09-20 18:13:00   来源：网络资源    双击单词自动翻译

　　(A)x = –3

　　(B)x = 0

　　?x = 6

　　(D)x = 12

　　(D)x = 24

　　2. Solve for x in the following inequality:　> 3

　　(A)x < –13

　　(B)x ≥ –13

　　?x ≤ –5

　　(D)x < –5

　　(D)x > –5

　　3. Solve for x in the following equation: 3 + |2x – 7| = x + 2

　　(A)x = –6

　　(B)x = 8

　　?x = {, 8}

　　(D)x = {6, 8}

　　(D)x = {, 6}

　　4. If x = 2y – 4 and y = 7s + 1, what is the value of s in terms of x?

　　(A)s =

　　(B)s =

　　?s =

　　(D)s =　+ 2 +

　　(D)s =

　　5. Jim and Ryan run laps around a track which is 1 /4 of a mile long. If Jim runs h laps per hour, Ryan runs half as fast as Jim, and Jim starts running half an hour before Ryan, how many miles farther than Ryan has Jim run two hours after Jim starts?

　　(A)

　　(B)

　　?

　　(D)

　　(D)

　　6. Ken buys a shirt on a 30% sale from its original price of 10 dollars. He then resells it at a 60% increase from the price at which he bought it. How much does Ken sell the shirt for?

　　(A)$4.20

　　(B)$11.20

　　?$13.00

　　(D)$13.30

　　(D)$14.20

　　7. A train leaves the station traveling due east at a rate of 45 miles per hour. A second train leaves a different station an hour later, traveling due west on the same track, going 60 miles per hour. If the stations are 255 miles apart, how many miles from the halfway point between the stations will the trains collide?

　　(A)0

　　(B)5

　　?7.5

　　(D)12.5

　　(D)25

　　8. A snowman weighing 250 pounds begins to melt in the spring. It loses 4% of its weight every day. How many full days will pass before it weighs less than 100 pounds?

　　(A)17

　　(B)22

　　?23

　　(D)27

　　(D)45

　　9. What is (a + b + 3c)(2a + 3b + 4c)?

　　(A)3a + 4b + 7c

　　(B)2a2 + 3b2 + 12c2

　　?2a2 + 10ac + 12c2

　　(D)2a2 + 3ab + 10ac + 9bc + 12c2

　　(D)2a2 + 3b2 + 12c2 + 5ab + 10ac + 13bc

　　10. Solve for x in the following equations: 3x2 + 24x – 27 = 0

　　(A)x = 1

　　(B)x = –9

　　?x = {1, –9}

　　(D)x = {–1, 9}

　　(D)x = {3, 27}

　　Explanations

　　1.　　　D

　　To solve this problem, just isolate the variable:

　　2.　　　D

　　Solving for a variable in an inequality is similar to solving for a variable in a normal equation, with one big difference: you isolate the variable. But remember that if you multiply or divide an inequality by a negative number, you must reverse the direction of the inequality symbol: