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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. 2sqrt4 + sqrt4 =
A chord is a line segment joining two points on a circle.
71 - 73 - 79
72
3sqrt4

2. Order of quadrants:
From northeast - counterclockwise. I - II - III - IV
67 - 71 - 73
20.5
The shortest arc between points A and B on a circle'S diameter.

3. 413.03 x 10^(-4) =
413.03 / 10^4 (move the decimal point 4 places to the left)
Cd
41 - 43 - 47
2sqrt6

4. A cylinder has surface area 22pi. If the cylinder has a height of 10 - what is its radius?
Ax^2 + bx + c where a -b and c are constants and a /=0
1
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
Diameter(Pi)

5. If an inequality is multiplied or divided by a negative number....
130pi
The overlapping sections.
The direction of the inequality is reversed.
IV

6. Which is greater? 200x^295 or 10x^294?
1
The objects within a set.
Cd
Relationship cannot be determined (what if x is negative?)

7. How many multiples does a given number have?
61 - 67
Infinite.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
The shortest arc between points A and B on a circle'S diameter.

8. How many digits are there between the decimal point and the first even digit in the decimal equivalent of 1/[(2^8)(5^3)]
A chord is a line segment joining two points on a circle.
2(pi)r^2 + 2(pi)rh
75:11
0

9. The number of degrees in the largest angle of a triangle inscribed in a circle - in which the diameter of the circle is one side of the triangle.
90 degrees
The sum of its digits is divisible by 3.
83.333%
61 - 67

10. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
F(x) - c
.0004809 X 10^11
F(x) + c
12! / 5!7! = 792

11. Find the surface area of a cylinder with radius 3 and height 12.
$11 -448
Undefined - because we can'T divide by 0.
9 & 6/7
90pi

12. What is the set of elements found in both A and B?
A set with a number of elements which can be counted.
(base*height) / 2
The interesection of A and B.
Two equal sides and two equal angles.

13. What is the 'union' of A and B?
The set of elements which can be found in either A or B.
72
0
The longest arc between points A and B on a circle'S diameter.

14. What is the percent formula?
90pi
Part = Percent X Whole
A subset.
The empty set - denoted by a circle with a diagonal through it.

15. a^2 - b^2 =
Relationship cannot be determined (what if x is negative?)
y = 2x^2 - 3
(a - b)(a + b)
A circle centered on the origin with radius 8.

16. When the 'a' in the parabola is negative...
The curve opens downward and the vertex is the maximum point on the graph.
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
... the square of the ratios of the corresponding sides.
A central angle is an angle formed by 2 radii.

17. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
(a + b)^2
1 & 37/132
x= (1.2)(.8)lw
28. n = 8 - k = 2. n! / k!(n-k)!

18. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
180 degrees
An isosceles right triangle.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
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)

19. Simplify (a^2 + b)^2 - (a^2 - b)^2
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)
4a^2(b)
F(x + c)
(p + q)/5

20. A number is divisible by 3 if ...
The sum of its digits is divisible by 3.
An infinite set.
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
Pi is the ratio of a circle'S circumference to its diameter.

21. 5/6 in percent?
83.333%
90
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
N! / (n-k)!

22. 5x^2 - 35x -55 = 0
27^(-4)
When the function is not defined for all real numbers -; only a subset of the real numbers.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

23. What is the 'Solution' for a system of linear equations?
The point of intersection of the systems.
3
72
.0004809 X 10^11

24. What does the graph x^2 + y^2 = 64 look like?
41 - 43 - 47
A circle centered on the origin with radius 8.
The direction of the inequality is reversed.
(base*height) / 2

25. Which quadrant is the upper left hand?
Two angles whose sum is 180.
Factors are few - multiples are many.
An isosceles right triangle.
II

26. What is the measure of an exterior angle of a regular pentagon?
10! / 3!(10-3)! = 120
Triangles with same measure and same side lengths.
The set of elements found in both A and B.
72

27. The slope of a line perpendicular to (a/b)?
500
An angle which is supplementary to an interior angle.
3sqrt4
Its negative reciprocal. (-b/a)

28. 30< all primes<40
A = I (1 + rt)
413.03 / 10^4 (move the decimal point 4 places to the left)
Two angles whose sum is 90.
31 - 37

29. Can the input value of a function have more than one output value (i.e. x: y - y1)?
No - the input value has exactly one output.
413.03 / 10^4 (move the decimal point 4 places to the left)
1
.0004809 X 10^11

30. Describe the relationship between the graphs of x^2 and (1/2)x^2
The second graph is less steep.
9 & 6/7
0
When the function is not defined for all real numbers -; only a subset of the real numbers.

31. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
Cd
7 / 1000
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.

32. (12sqrt15) / (2sqrt5) =
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
A tangent is a line that only touches one point on the circumference of a circle.
Even

33. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
1/2 times 7/3
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
4.25 - 6 - 22
Arc length = (n/360) x pi(2r) where n is the number of degrees.

34. The perimeter of a square is 48 inches. The length of its diagonal is:
4:5
A set with a number of elements which can be counted.
12sqrt2
Relationship cannot be determined (what if x is negative?)

35. What is the absolute value function?
The steeper the slope.
Lies opposite the greater angle
Undefined - because we can'T divide by 0.
G(x) = {x}

36. 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
18
A reflection about the axis.
1/2 times 7/3
71 - 73 - 79

37. 5/8 in percent?
A tangent is a line that only touches one point on the circumference of a circle.
62.5%
The two xes after factoring.
1.0843 X 10^11

38. What is an isoceles triangle?
Two equal sides and two equal angles.
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
A grouping of the members within a set based on a shared characteristic.
1

39. How to find the diagonal of a rectangular solid?
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
10
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 found in both A and B.

40. What is the 'Restricted domain of a function'?
A tangent is a line that only touches one point on the circumference of a circle.
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
When the function is not defined for all real numbers -; only a subset of the real numbers.
F(x + c)

41. The four angles around a point measure y - 2y - 35 and 55 respectively. What is the value of y?
Lies opposite the greater angle
90
Yes - like radicals can be added/subtracted.
Divide by 100.

42. Can you add sqrt 3 and sqrt 5?
4.25 - 6 - 22
No - only like radicals can be added.
1/(x^y)
3 - -3

43. If Madagascar'S exports totaled 1.3 billion in 2009 - and 4% came from China - what was the value in millions of the country'S exports to China?
2^9 / 2 = 256
52
Its negative reciprocal. (-b/a)
Part = Percent X Whole

44. What is the graph of f(x) shifted downward c units or spaces?
13
F(x) - c
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

45. What does scientific notation mean?
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...
55%
(a + b)^2
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

46. Area of a triangle?
Ax^2 + bx + c where a -b and c are constants and a /=0
Cd
55%
(base*height) / 2

47. What is the sum of the angles of a triangle?
180 degrees
Sector area = (n/360) X (pi)r^2
Members or elements
No - only like radicals can be added.

48. Legs: 3 - 4. Hypotenuse?
0
5
2 & 3/7
27^(-4)

49. 10<all primes<20
11 - 13 - 17 - 19
9 & 6/7
N! / (k!)(n-k)!
(a - b)^2

50. What are the real numbers?
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)
72
67 - 71 - 73
37.5%