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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. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
Lies opposite the greater angle
y = (x + 5)/2
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

2. 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?
55%
A = pi(r^2)
Even
52

3. Simplify 4sqrt21 X 5sqrt2 / 10sqrt7
1/(x^y)
2sqrt6
The overlapping sections.
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

4. What is a central angle?
The empty set - denoted by a circle with a diagonal through it.
A central angle is an angle formed by 2 radii.
3
A reflection about the axis.

5. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
28. n = 8 - k = 2. n! / k!(n-k)!
When the function is not defined for all real numbers -; only a subset of the real numbers.
II
180 degrees

6. Area of a triangle?
The set of elements which can be found in either A or B.
180
(base*height) / 2
C = 2(pi)r

7. 10^6 has how many zeroes?
(a + b)^2
(amount of increase/original price) x 100%
An expression with just one term (-6x - 2a^2)
6

8. 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?
10! / 3!(10-3)! = 120
F(x-c)
An isosceles right triangle.
62.5%

9. Evaluate 4/11 + 11/12
The curve opens downward and the vertex is the maximum point on the graph.
The union of A and B.
Indeterminable.
1 & 37/132

10. Describe the relationship between the graphs of x^2 and (1/2)x^2
The second graph is less steep.
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
I
1/a^6

11. 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?
130pi
Divide by 100.
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.
y = 2x^2 - 3

12. To multiply a number by 10^x
Yes - like radicals can be added/subtracted.
Move the decimal point to the right x places
An infinite set.
An angle which is supplementary to an interior angle.

13. What is the side length of an equilateral triangle with altitude 6?
(n-2) x 180
(amount of increase/original price) x 100%
12! / 5!7! = 792
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...

14. How many digits are there between the decimal point and the first even digit in the decimal equivalent of 1/[(2^8)(5^3)]
Its divisible by 2 and by 3.
G(x) = {x}
5
0

15. 5x^2 - 35x -55 = 0
500
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
1
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)

16. 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
Triangles with same measure and same side lengths.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
12sqrt2
18

17. What are the members or elements of a set?
C = 2(pi)r
4:5
x^(4+7) = x^11
The objects within a set.

18. The ratio of the areas of two similar polygons is ...
1
... the square of the ratios of the corresponding sides.
Ax^2 + bx + c where a -b and c are constants and a /=0
500

19. What is a piecewise equation?
Two angles whose sum is 90.
Factors are few - multiples are many.
A grouping of the members within a set based on a shared characteristic.
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.

20. Which quadrant is the upper left hand?
5
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
III
II

21. a^0 =
A tangent is a line that only touches one point on the circumference of a circle.
1
I
Angle/360 x 2(pi)r

22. Define a 'Term' -
0
Yes - like radicals can be added/subtracted.
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)
4096

23. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
An isosceles right triangle.
37.5%
288 (8 9 4)
70

24. Convert 0.7% to a fraction.
7 / 1000
11 - 13 - 17 - 19
The objects within a set.
Infinite.

25. x^2 = 9. What is the value of x?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
83.333%
3 - -3
72

26. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
23 - 29
Two angles whose sum is 90.
Cd
83.333%

27. Define a 'monomial'
An expression with just one term (-6x - 2a^2)
The second graph is less steep.
4725
10! / 3!(10-3)! = 120

28. Is 0 even or odd?
1
Even
The point of intersection of the systems.
11 - 13 - 17 - 19

29. What is the set of elements found in both A and B?
10! / (10-3)! = 720
5 OR -5
3sqrt4
The interesection of A and B.

30. Factor x^2 - xy + x.
$11 -448
28. n = 8 - k = 2. n! / k!(n-k)!
x(x - y + 1)
2sqrt6

31. What are the smallest three prime numbers greater than 65?
20.5
A = pi(r^2)
An expression with just one term (-6x - 2a^2)
67 - 71 - 73

32. How to find the area of a sector?
Angle/360 x (pi)r^2
12sqrt2
Divide by 100.
A reflection about the axis.

33. 413.03 x 10^(-4) =
II
87.5%
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
413.03 / 10^4 (move the decimal point 4 places to the left)

34. To convert a percent to a fraction....
A central angle is an angle formed by 2 radii.
72
Divide by 100.
Angle/360 x 2(pi)r

35. What is the 'Solution' for a set of inequalities.
Its negative reciprocal. (-b/a)
x^(4+7) = x^11
Diameter(Pi)
The overlapping sections.

36. 40 < all primes<50
41 - 43 - 47
Lies opposite the greater angle
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
.0004809 X 10^11

37. Can the input value of a function have more than one output value (i.e. x: y - y1)?
Angle/360 x 2(pi)r
No - the input value has exactly one output.
1.7
The objects within a set.

38. Simplify the expression [(b^2 - c^2) / (b - c)]
(b + c)
27^(-4)
A subset.
Divide by 100.

39. What is the slope of a horizontal line?
37.5%
Its divisible by 2 and by 3.
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
0

40. Legs 5 - 12. Hypotenuse?
13
x= (1.2)(.8)lw
3/2 - 5/3
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)

41. Suppose that the graph of f(x) is the result of stretching y=x + 5 away from the x-axis by a factor of 2. What is the new equation for the graph f(x)?
The sum of digits is divisible by 9.
Two angles whose sum is 90.
y = (x + 5)/2
180 degrees

42. Surface area for a cylinder?
The two xes after factoring.
2(pi)r^2 + 2(pi)rh
y = 2x^2 - 3
4:5

43. Which quadrant is the upper right hand?
I
Diameter(Pi)
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
Triangles with same measure and same side lengths.

44. Can you add sqrt 3 and sqrt 5?
No - only like radicals can be added.
An isosceles right triangle.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
III

45. If 10800 is invested at a simple interest rate of 4% - what is the value of the investment after 18 months?
(a + b)^2
$11 -448
(n-2) x 180
(a - b)^2

46. What are the real numbers?
A set with no members - denoted by a circle with a diagonal through it.
(base*height) / 2
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)
x= (1.2)(.8)lw

47. Max and Min lengths for a side of a triangle?
The third side is greater than the difference and less than the sum.
10
7 / 1000
0

48. What is the 'Range' of a function?
When the function is not defined for all real numbers -; only a subset of the real numbers.
130pi
The set of output values for a function.
90

49. What is the empty set?
12.5%
1
A set with no members - denoted by a circle with a diagonal through it.
A central angle is an angle formed by 2 radii.

50. 1/8 in percent?
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
130pi
12.5%
62.5%