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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. 20<all primes<30
F(x) + c
52
23 - 29
The union of A and B.

2. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
G(x) = {x}
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
3
90

3. Formula for the area of a sector of a circle?
Sector area = (n/360) X (pi)r^2
10
1/(x^y)
The empty set - denoted by a circle with a diagonal through it.

4. (a^-1)/a^5
Sector area = (n/360) X (pi)r^2
1:1:sqrt2
(amount of increase/original price) x 100%
1/a^6

5. To convert a percent to a fraction....
Move the decimal point to the right x places
The interesection of A and B.
Divide by 100.
2.592 kg

6. 4.809 X 10^7 =
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)
3
.0004809 X 10^11
3/2 - 5/3

7. 413.03 x 10^(-4) =
13pi / 2
3 - -3
413.03 / 10^4 (move the decimal point 4 places to the left)
90 degrees

8. Factor a^2 + 2ab + b^2
20.5
All numbers multiples of 1.
(a + b)^2
3sqrt4

9. Circumference of a circle?
Diameter(Pi)
The set of output values for a function.
Infinite.
G(x) = {x}

10. Order of quadrants:
4a^2(b)
A set with a number of elements which can be counted.
1:sqrt3:2
From northeast - counterclockwise. I - II - III - IV

11. Which quadrant is the lower left hand?
The sum of digits is divisible by 9.
III
41 - 43 - 47
An expression with just one term (-6x - 2a^2)

12. 1/2 divided by 3/7 is the same as
16.6666%
3sqrt4
1/2 times 7/3
x(x - y + 1)

13. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
Its last two digits are divisible by 4.
...multiply by 100.
The set of output values for a function.
A reflection about the axis.

14. What are congruent triangles?
Triangles with same measure and same side lengths.
72
Indeterminable.
23 - 29

15. What is the surface area of a cylinder with radius 5 and height 8?
130pi
(base*height) / 2
90pi
6 : 1 : 2

16. Simplify the expression [(b^2 - c^2) / (b - c)]
Sqrt 12
(b + c)
70
0

17. How to determine percent increase?
1
(amount of increase/original price) x 100%
Indeterminable.
10! / 3!(10-3)! = 120

18. What is a set with no members called?
The objects within a set.
The empty set - denoted by a circle with a diagonal through it.
12! / 5!7! = 792
The sum of its digits is divisible by 3.

19. 25^(1/2) or sqrt. 25 =
5 OR -5
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
83.333%
1:1:sqrt2

20. What are the integers?
3
The set of output values for a function.
All numbers multiples of 1.
67 - 71 - 73

21. 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?
A tangent is a line that only touches one point on the circumference of a circle.
0
N! / (n-k)!
Factors are few - multiples are many.

22. Solve the quadratic equation ax^2 + bx + c= 0
75:11
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
441000 = 1 10 10 10 21 * 21
12sqrt2

23. How many sides does a hexagon have?
Angle/360 x 2(pi)r
x^(2(4)) =x^8 = (x^4)^2
6
0

24. A number is divisible by 9 if...
Triangles with same measure and same side lengths.
7 / 1000
The sum of digits is divisible by 9.
Pi is the ratio of a circle'S circumference to its diameter.

25. 7/8 in percent?
87.5%
Its divisible by 2 and by 3.
The set of elements found in both A and B.
A set with no members - denoted by a circle with a diagonal through it.

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))?
x(x - y + 1)
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)
20.5
The third side is greater than the difference and less than the sum.

27. What is an exterior angle?
A reflection about the origin.
An angle which is supplementary to an interior angle.
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
4:5

28. Simplify the expression (p^2 - q^2)/ -5(q - p)
61 - 67
F(x) + c
0
(p + q)/5

29. If the two sides of a triangle are unequal then the longer side...
441000 = 1 10 10 10 21 * 21
Lies opposite the greater angle
Sector area = (n/360) X (pi)r^2
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.

30. To multiply a number by 10^x
13
Arc length = (n/360) x pi(2r) where n is the number of degrees.
A circle centered at -2 - -2 with radius 3.
Move the decimal point to the right x places

31. What are the irrational numbers?

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32. What is the order of operations?
.0004809 X 10^11
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
441000 = 1 10 10 10 21 * 21

33. Define an 'expression'.
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)
The sum of digits is divisible by 9.
When the function is not defined for all real numbers -; only a subset of the real numbers.
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.

34. What is the set of elements which can be found in either A or B?
The union of A and B.
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.
Its negative reciprocal. (-b/a)
An arc is a portion of a circumference of a circle.

35. Nine coins are tossed simultaneously. In how many of the outcomes will the fourth coin tossed show heads?
All numbers multiples of 1.
Undefined
4a^2(b)
2^9 / 2 = 256

36. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
Lies opposite the greater angle
A reflection about the origin.
3sqrt4
I

37. What is the 'Solution' for a set of inequalities.
Move the decimal point to the right x places
The overlapping sections.
90pi
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)

38. Describe the relationship between the graphs of x^2 and (1/2)x^2
The second graph is less steep.
y = 2x^2 - 3
3/2 - 5/3
6 : 1 : 2

39. a^0 =
6
True
(a - b)^2
1

40. What are the roots of the quadrinomial x^2 + 2x + 1?
1.0843 X 10^11
72
The two xes after factoring.
A reflection about the origin.

41. (x^2)^4
28. n = 8 - k = 2. n! / k!(n-k)!
x^(2(4)) =x^8 = (x^4)^2
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
II

42. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
0
A 30-60-90 triangle.
3
(base*height) / 2

43. To convert a decimal to a percent...
...multiply by 100.
An isosceles right triangle.
N! / (n-k)!
A circle centered at -2 - -2 with radius 3.

44. Reduce: 4.8 : 0.8 : 1.6
6 : 1 : 2
90 degrees
1/2 times 7/3
Divide by 100.

45. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
8
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
31 - 37
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.

46. What is the area of a regular hexagon with side 6?
3sqrt4
The curve opens downward and the vertex is the maximum point on the graph.
A circle centered on the origin with radius 8.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

47. Formula to find a circle'S circumference from its diameter?
1:1:sqrt2
C = (pi)d
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
Lies opposite the greater angle

48. Convert 0.7% to a fraction.
The third side is greater than the difference and less than the sum.
7 / 1000
Its last two digits are divisible by 4.
130pi

49. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
70
y = 2x^2 - 3
9 : 25
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

50. What is the name of set with a number of elements which cannot be counted?
x= (1.2)(.8)lw
90pi
An infinite set.
(base*height) / 2