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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. What are congruent triangles?
1
Triangles with same measure and same side lengths.
52
13pi / 2

2. What is the 'domain' of a function?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
When the function is not defined for all real numbers -; only a subset of the real numbers.
The set of input values for a function.
A chord is a line segment joining two points on a circle.

3. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
12! / 5!7! = 792
From northeast - counterclockwise. I - II - III - IV

4. Can the output value of a function have more than one input value?
Yes. [i.e. f(x) = x^2 - 1
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
2^9 / 2 = 256
13

5. Define a 'monomial'
I
31 - 37
x(x - y + 1)
An expression with just one term (-6x - 2a^2)

6. What is a major arc?

7. What are complementary angles?
Two angles whose sum is 90.
(a - b)(a + b)
Angle/360 x 2(pi)r
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

8. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
Factors are few - multiples are many.
An arc is a portion of a circumference of a circle.
2
8

9. 70 < all primes< 80
2sqrt6
71 - 73 - 79
75:11
4725

10. What is the ratio of the sides of an isosceles right triangle?
90 degrees
1:1:sqrt2
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
The two xes after factoring.

11. What is the formula for compounded interest?
A 30-60-90 triangle.
A= I (1 + (r/c))^tC - where I is the investment - C is the number of times compounded annually - and t is the number of years.
3sqrt4
The set of input values for a function.

12. There are 10 finalists for the school spelling bee. A first - second - and third place trophy will be awarded. How many different people can get the three prizes?
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
10! / 3!(10-3)! = 120
3/2 - 5/3
The set of elements found in both A and B.

13. How to find the circumference of a circle which circumscribes a square?
1:sqrt3:2
4725
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
A set with a number of elements which can be counted.

14. 2sqrt4 + sqrt4 =
A term is a numerical constant or the product (or quotient) of a numerical constant and one or more variables. (3x - 4x^2 and 2a/c)
72
130pi
3sqrt4

15. When the 'a' in the parabola is negative...
The curve opens downward and the vertex is the maximum point on the graph.
The sum of its digits is divisible by 3.
Sector area = (n/360) X (pi)r^2
6

16. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
(b + c)
71 - 73 - 79
27^(-4)

17. 4.809 X 10^7 =
61 - 67
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
The point of intersection of the systems.
.0004809 X 10^11

18. A number is divisible by 4 is...
Divide by 100.
N! / (n-k)!
Its last two digits are divisible by 4.
31 - 37

19. What is a minor arc?

20. What is the 'union' of A and B?
The set of elements which can be found in either A or B.
2.4. We calculate the area (6) and then turn the triangle on its side and use x as the height to calculate again. (5x)/2=6
Even
Yes - like radicals can be added/subtracted.

21. A brick with dimensions 10. 15 and 25 weighs 1.5 kg. A second brick (same density) has dimensions 12 - 18 - and 30. What is the weight of the second brick?
8
5
2.592 kg
1:1:sqrt2

22. What is the percent formula?
10
The third side is greater than the difference and less than the sum.
Part = Percent X Whole
(base*height) / 2

23. x^6 / x^3
An angle which is supplementary to an interior angle.
Cd
x^(6-3) = x^3
Its last two digits are divisible by 4.

24. What is a central angle?
A central angle is an angle formed by 2 radii.
2^9 / 2 = 256
1
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)

25. 5x^2 - 35x -55 = 0
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
23 - 29
Two angles whose sum is 180.
III

26. What is an arc of a circle?
The curve opens upward and the vertex is the minimal point on the graph.
C = (pi)d
Yes. [i.e. f(x) = x^2 - 1
An arc is a portion of a circumference of a circle.

27. What is the intersection of A and B?
5
A tangent is a line that only touches one point on the circumference of a circle.
The set of elements found in both A and B.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

28. 60 < all primes <70
61 - 67
F(x + c)
5
(n-2) x 180

29. When the 'a' in a parabola is positive....
3 - -3
C = (pi)d
x^(4+7) = x^11
The curve opens upward and the vertex is the minimal point on the graph.

30. x^2 = 9. What is the value of x?
3 - -3
The shortest arc between points A and B on a circle'S diameter.
The greatest value minus the smallest.
A set with no members - denoted by a circle with a diagonal through it.

31. Max and Min lengths for a side of a triangle?
288 (8 9 4)
The third side is greater than the difference and less than the sum.
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
A reflection about the origin.

32. What are the irrational numbers?

33. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
III
16.6666%
A reflection about the axis.

34. Write 10 -843 X 10^7 in scientific notation
1.0843 X 10^11
Its divisible by 2 and by 3.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
The longest arc between points A and B on a circle'S diameter.

35. What are the smallest three prime numbers greater than 65?
Diameter(Pi)
67 - 71 - 73
Factors are few - multiples are many.
A set with a number of elements which can be counted.

36. 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?
N! / (n-k)!
(n-2) x 180
1:1:sqrt2
18

37. What is the slope of a vertical line?

38. 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?
N! / (k!)(n-k)!
(b + c)
y = 2x^2 - 3
67 - 71 - 73

39. What is the name for a grouping of the members within a set based on a shared characteristic?
A subset.
The steeper the slope.
A central angle is an angle formed by 2 radii.
The interesection of A and B.

40. Area of a triangle?
90
(a + b)^2
70
(base*height) / 2

41. 50 < all primes< 60
70
7 / 1000
53 - 59
(a + b)^2

42. Suppose that the graph of f(x) is the result of sliding the graph of y=2x^2 down 3 units of spaces. What is the new equation?
IV
$11 -448
y = 2x^2 - 3
When the function is not defined for all real numbers -; only a subset of the real numbers.

43. Evaluate (4^3)^2
A= I (1 + (r/c))^tC - where I is the investment - C is the number of times compounded annually - and t is the number of years.
3/2 - 5/3
16.6666%
4096

44. What is the 'Solution' for a set of inequalities.
The point of intersection of the systems.
The overlapping sections.
87.5%
3

45. a^2 - b^2 =
(a + b)^2
An angle which is supplementary to an interior angle.
$11 -448
(a - b)(a + b)

46. 413.03 x 10^(-4) =
71 - 73 - 79
27^(-4)
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
413.03 / 10^4 (move the decimal point 4 places to the left)

47. (6sqrt3) x (2sqrt5) =
67 - 71 - 73
A set with no members - denoted by a circle with a diagonal through it.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
F(x + c)

48. If the two sides of a triangle are unequal then the longer side...
A circle centered at -2 - -2 with radius 3.
180 degrees
F(x) - c
Lies opposite the greater angle

49. How many sides does a hexagon have?
A circle centered at -2 - -2 with radius 3.
6
Triangles with same measure and same side lengths.
C = (pi)d

50. Employee X is paid 19.50 per hour no matter how many a week. Employee Y earns 18 for the first 40 and 1.5 the hourly wage for every hour after that. If both earned the same amount and worked the same in one week - how many did each work?
Area of the base X height = (pi)hr^2
48
(amount of increase/original price) x 100%
3