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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. 0^0
The union of A and B.
Factors are few - multiples are many.
23 - 29
Undefined

2. Formula for the area of a sector of a circle?
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
Sector area = (n/360) X (pi)r^2
2.592 kg
Members or elements

3. 7/8 in percent?
Triangles with same measure and same side lengths.
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
The set of output values for a function.
87.5%

4. If the 80th percentile of the measurements is 72degrees - about how many measurments are between 69 degrees and 72 degrees? Round your answer to the nearest tenth
Sector area = (n/360) X (pi)r^2
N! / (k!)(n-k)!
No - the input value has exactly one output.
18

5. What is the side length of an equilateral triangle with altitude 6?
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...
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
A central angle is an angle formed by 2 radii.
(a + b)^2

6. Formula of rectangle where l increases by 20% and w decreases by 20%
55%
1
x= (1.2)(.8)lw
The longest arc between points A and B on a circle'S diameter.

7. Which quadrant is the lower left hand?
28. n = 8 - k = 2. n! / k!(n-k)!
1/a^6
III
(base*height) / 2

8. What is the maximum value for the function g(x) = (-2x^2) -1?
Even
Relationship cannot be determined (what if x is negative?)
1
1/a^6

9. 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?
500
83.333%
2.592 kg
The objects within a set.

10. Which quandrant is the lower right hand?
1
A circle centered at -2 - -2 with radius 3.
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
IV

11. If r - t - s & u are distinct - consecutive prime numbers - less than 31 - which of the following could be an average of them (4 - 4.25 - 6 - 9 - 24 - 22 - 24)
Pi is the ratio of a circle'S circumference to its diameter.
1
12! / 5!7! = 792
4.25 - 6 - 22

12. What is the name for a grouping of the members within a set based on a shared characteristic?
A subset.
The sum of digits is divisible by 9.
5 OR -5
Infinite.

13. What is the set of elements which can be found in either A or B?
The union of A and B.
A set with no members - denoted by a circle with a diagonal through it.
1/2 times 7/3
(p + q)/5

14. What is an exterior angle?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
When the function is not defined for all real numbers -; only a subset of the real numbers.
Indeterminable.
An angle which is supplementary to an interior angle.

15. a^2 + 2ab + b^2
9 & 6/7
(amount of increase/original price) x 100%
(a + b)^2
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16

16. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
An isosceles right triangle.
Its last two digits are divisible by 4.
A chord is a line segment joining two points on a circle.
A set with no members - denoted by a circle with a diagonal through it.

17. Factor x^2 - xy + x.
x(x - y + 1)
4725
Lies opposite the greater angle
The shortest arc between points A and B on a circle'S diameter.

18. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
The two xes after factoring.
The third side is greater than the difference and less than the sum.
10! / 3!(10-3)! = 120
8

19. Can you add sqrt 3 and sqrt 5?
2sqrt6
No - only like radicals can be added.
4:5
The third side is greater than the difference and less than the sum.

20. Order of quadrants:
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
2(pi)r^2 + 2(pi)rh
From northeast - counterclockwise. I - II - III - IV
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16

21. The larger the absolute value of the slope...
2sqrt6
The steeper the slope.
3sqrt4
5 OR -5

22. Formula for the area of a circle?
II
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
1
A = pi(r^2)

23. What is the 'union' of A and B?
7 / 1000
The second graph is less steep.
3
The set of elements which can be found in either A or B.

24. What is the measure of an exterior angle of a regular pentagon?
A = pi(r^2)
No - only like radicals can be added.
72
y = 2x^2 - 3

25. Legs 5 - 12. Hypotenuse?
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
70
13
An angle which is supplementary to an interior angle.

26. If a=-1 and b=3 - what is the value of (4(a^3)(b^2) - 12(a^2)(b^5)) / (16(a^3)(b^2))?
10! / (10-3)! = 720
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
20.5
The longest arc between points A and B on a circle'S diameter.

27. 5x^2 - 35x -55 = 0
(n-2) x 180
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
3 - -3
Relationship cannot be determined (what if x is negative?)

28. Define a 'Term' -
C = (pi)d
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)
The longest arc between points A and B on a circle'S diameter.
(b + c)

29. Can you simplify sqrt72?
A set with no members - denoted by a circle with a diagonal through it.
55%
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
N! / (k!)(n-k)!

30. Formula to find a circle'S circumference from its diameter?
From northeast - counterclockwise. I - II - III - IV
C = (pi)d
A reflection about the origin.
(12/2) x (sqrt15 / sqrt5) = 6sqrt3

31. 5/6 in percent?
3/2 - 5/3
83.333%
Its divisible by 2 and by 3.
x(x - y + 1)

32. What is a set with no members called?
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
The empty set - denoted by a circle with a diagonal through it.
48
0

33. Which is greater? 27^(-4) or 9^(-8)
1/2 times 7/3
Diameter(Pi)
27^(-4)
12.5%

34. (a^-1)/a^5
20.5
$11 -448
C = 2(pi)r
1/a^6

35. Simplify 4sqrt21 X 5sqrt2 / 10sqrt7
An isosceles right triangle.
2sqrt6
Two angles whose sum is 180.
10! / (10-3)! = 720

36. Which is greater? 64^5 or 16^8
180
x^(6-3) = x^3
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
A set with no members - denoted by a circle with a diagonal through it.

37. What is the name of set with a number of elements which cannot be counted?
...multiply by 100.
The set of input values for a function.
An infinite set.
52

38. What is the 'domain' of a function?
441000 = 1 10 10 10 21 * 21
A central angle is an angle formed by 2 radii.
The set of input values for a function.
1/(x^y)

39. What are the members or elements of a set?
Members or elements
The greatest value minus the smallest.
2.592 kg
The objects within a set.

40. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
A circle centered at -2 - -2 with radius 3.
Angle/360 x 2(pi)r
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
288 (8 9 4)

41. 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?
4:5
x^(6-3) = x^3
The empty set - denoted by a circle with a diagonal through it.
441000 = 1 10 10 10 21 * 21

42. To convert a decimal to a percent...
y = (x + 5)/2
Two angles whose sum is 180.
Sector area = (n/360) X (pi)r^2
...multiply by 100.

43. What is the ratio of the surface area of a cube with an edge of 10 to the surface area of a rectangular solid with dimensions 2 - 4 - and 6?
(a - b)(a + b)
Lies opposite the greater angle
(amount of decrease/original price) x 100%
75:11

44. x^(-y)=
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
1.0843 X 10^11
9 : 25
1/(x^y)

45. Simplify 9^(1/2) X 4^3 X 2^(-6)?
F(x + c)
...multiply by 100.
Two angles whose sum is 180.
3

46. What is the sum of the angles of a triangle?
180 degrees
6
71 - 73 - 79
130pi

47. What is a piecewise equation?
A reflection about the origin.
7 / 1000
Its divisible by 2 and by 3.
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.

48. What are the irrational numbers?

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49. 4.809 X 10^7 =
A 30-60-90 triangle.
.0004809 X 10^11
1.7
9 & 6/7

50. What is the empty set?
F(x-c)
72
A set with no members - denoted by a circle with a diagonal through it.
Its divisible by 2 and by 3.