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GRE Math: Common Errors

Subjects : gre, math

Instructions:

Answer 50 questions in 15 minutes.
If you are not ready to take this test, you can study here.
Match each statement with the correct term.
Don't refresh. All questions and answers are randomly picked and ordered every time you load a test.

This is a study tool. The 3 wrong answers for each question are randomly chosen from answers to other questions. So, you might find at times the answers obvious, but you will see it re-enforces your understanding as you take the test each time.

1. Define an 'expression'.
Cd
3sqrt4
An algebraic expression is a combination of one of more terms. Terms in an expression are separated by either addition or subtraction signs. (3xy - 4ab - -5cd - x^2 + x - 1)
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

2. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
...multiply by 100.
10! / (10-3)! = 720
Angle/360 x 2(pi)r
28. n = 8 - k = 2. n! / k!(n-k)!

3. What is the 'Range' of a function?
A set with a number of elements which can be counted.
C = 2(pi)r
16.6666%
The set of output values for a function.

4. Factor a^2 + 2ab + b^2
The sum of its digits is divisible by 3.
87.5%
1
(a + b)^2

5. Suppose you have a set of n objects - and you want to select k of them - but the order doesn'T matter. What formula do you use to determine the number of combinations of n objects taken k at a time?
The sum of its digits is divisible by 3.
$11 -448
N! / (k!)(n-k)!
C = (pi)d

6. Volume for a cylinder?
(amount of increase/original price) x 100%
28. n = 8 - k = 2. n! / k!(n-k)!
Area of the base X height = (pi)hr^2
The shortest arc between points A and B on a circle'S diameter.

7. 10^6 has how many zeroes?
Members or elements
Part = Percent X Whole
6
0

8. Simplify 9^(1/2) X 4^3 X 2^(-6)?
Pi is the ratio of a circle'S circumference to its diameter.
3
(a + b)^2
10! / 3!(10-3)! = 120

9. Circumference of a circle?
Diameter(Pi)
A reflection about the axis.
The curve opens downward and the vertex is the maximum point on the graph.
F(x) - c

10. What are the smallest three prime numbers greater than 65?
10! / (10-3)! = 720
67 - 71 - 73
(a - b)(a + b)
A set with no members - denoted by a circle with a diagonal through it.

11. Max and Min lengths for a side of a triangle?
72
The third side is greater than the difference and less than the sum.
F(x) + c
x^(4+7) = x^11

12. If you have a set of n objects - but you only want to order k of them - what formula do you use to determine the number of permutations?
1
N! / (n-k)!
(a - b)(a + b)
87.5%

13. What is the surface area of a cylinder with radius 5 and height 8?
9 : 25
130pi
x^(6-3) = x^3
12.5%

14. x^2 = 9. What is the value of x?
A = I (1 + rt)
3 - -3
x^(6-3) = x^3
The empty set - denoted by a circle with a diagonal through it.

15. What is the area of a regular hexagon with side 6?
2.592 kg
5 OR -5
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

16. x^(-y)=
The empty set - denoted by a circle with a diagonal through it.
1/(x^y)
9 : 25
The objects within a set.

17. What are complementary angles?
Two angles whose sum is 90.
10
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
y = (x + 5)/2

18. There are 10 finalists for the school spelling bee. A first - second - and third place trophy will be awarded. In how many ways can the judges award the 3 prizes?
10! / (10-3)! = 720
2.592 kg
4:5
C = (pi)d

19. Reduce: 4.8 : 0.8 : 1.6
1.7
Two equal sides and two equal angles.
6 : 1 : 2
72

20. 5x^2 - 35x -55 = 0
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
A set with no members - denoted by a circle with a diagonal through it.
The curve opens upward and the vertex is the minimal point on the graph.
An infinite set.

21. Define a 'monomial'
An expression with just one term (-6x - 2a^2)
Members or elements
(a - b)(a + b)
G(x) = {x}

22. 1/2 divided by 3/7 is the same as
.0004809 X 10^11
1/2 times 7/3
All the numbers on the number line (negative - rational - irrational - decimal - integer). All the numbers on the GRE are real. (-2 - 1 - .25 - 1/2 - pi)
61 - 67

23. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
A circle centered at -2 - -2 with radius 3.
The direction of the inequality is reversed.
12sqrt2
Two angles whose sum is 90.

24. What is the 'Restricted domain of a function'?
The point of intersection of the systems.
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
1.7
When the function is not defined for all real numbers -; only a subset of the real numbers.

25. How many digits are there between the decimal point and the first even digit in the decimal equivalent of 1/[(2^8)(5^3)]
An arc is a portion of a circumference of a circle.
180
0
$3 -500 in the 9% and $2 -500 in the 7%.

26. What is the side length of an equilateral triangle with altitude 6?
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
4sqrt3. The triangle can be divided into two equal 30-60-90 triangles with side 6 as the side in which 6 = xsqrt3. So x =2sqrt3...
N! / (n-k)!
y = 2x^2 - 3

27. Simplify the expression [(b^2 - c^2) / (b - c)]
12! / 5!7! = 792
A subset.
(b + c)
441000 = 1 10 10 10 21 * 21

28. What is the maximum value for the function g(x) = (-2x^2) -1?
Diameter(Pi)
1
From northeast - counterclockwise. I - II - III - IV
All numbers multiples of 1.

29. A cylinder has a surface area of 22pi. If the cylinder has a height of 10 - what is the radius?
3sqrt4
x(x - y + 1)
Two equal sides and two equal angles.
1

30. What is the sum of the angles of a triangle?
31 - 37
180 degrees
70
62.5%

31. What is the 'Range' of a series of numbers?
The greatest value minus the smallest.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
Undefined - because we can'T divide by 0.
90

32. 25^(1/2) or sqrt. 25 =
When the function is not defined for all real numbers -; only a subset of the real numbers.
5 OR -5
A central angle is an angle formed by 2 radii.
71 - 73 - 79

33. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
Ax^2 + bx + c where a -b and c are constants and a /=0
F(x + c)
1
8

34. a^2 + 2ab + b^2
An infinite set.
(a + b)^2
A set with no members - denoted by a circle with a diagonal through it.
16.6666%

35. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
Two angles whose sum is 90.
4725
12.5%
The greatest value minus the smallest.

36. A company places a 6-symbol code on each product. The code consists of the letter T - followed by 3 numerical digits - and then 2 consonants (Y is a conson). How many codes are possible?
y = (x + 5)/2
4sqrt3. The triangle can be divided into two equal 30-60-90 triangles with side 6 as the side in which 6 = xsqrt3. So x =2sqrt3...
23 - 29
441000 = 1 10 10 10 21 * 21

37. (-1)^3 =
G(x) = {x}
1
90 degrees
13pi / 2

38. What percent of 40 is 22?
G(x) = {x}
5 OR -5
1.7
55%

39. 50 < all primes< 60
The third side is greater than the difference and less than the sum.
3
53 - 59
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

40. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
2 & 3/7
A 30-60-90 triangle.
The objects within a set.
7 / 1000

41. sqrt 2(sqrt 6)=
3
The union of A and B.
70
Sqrt 12

42. How to find the diagonal of a rectangular solid?
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
The set of elements which can be found in either A or B.
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
413.03 / 10^4 (move the decimal point 4 places to the left)

43. What is the formula for computing simple interest?
N! / (k!)(n-k)!
N! / (n-k)!
288 (8 9 4)
A = I (1 + rt)

44. (6sqrt3) x (2sqrt5) =
A reflection about the axis.
An arc is a portion of a circumference of a circle.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
...multiply by 100.

45. What is the ratio of the sides of an isosceles right triangle?
(b + c)
1
1:1:sqrt2
Sqrt 12

46. What is the intersection of A and B?
A 30-60-90 triangle.
The set of elements found in both A and B.
Cd
52

47. Number of degrees in a triangle
IV
Infinite.
4a^2(b)
180

48. What is a central angle?
4sqrt3. The triangle can be divided into two equal 30-60-90 triangles with side 6 as the side in which 6 = xsqrt3. So x =2sqrt3...
A central angle is an angle formed by 2 radii.
12! / 5!7! = 792
Sqrt 12

49. What is the slope of a horizontal line?
x^(2(4)) =x^8 = (x^4)^2
Relationship cannot be determined (what if x is negative?)
13pi / 2
0

50. Find the surface area of a cylinder with radius 3 and height 12.
90pi
1 & 37/132
6
1