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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. Simplify 9^(1/2) X 4^3 X 2^(-6)?
3
1
61 - 67
12! / 5!7! = 792

2. 8.84 / 5.2
1.7
1 & 37/132
F(x + c)
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.

3. What percent of 40 is 22?
...multiply by 100.
52
55%
The third side is greater than the difference and less than the sum.

4. Which is greater? 27^(-4) or 9^(-8)
288 (8 9 4)
27^(-4)
III
An arc is a portion of a circumference of a circle.

5. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
A 30-60-90 triangle.
...multiply by 100.
F(x) + c
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

6. Factor x^2 - xy + x.
The shortest arc between points A and B on a circle'S diameter.
12! / 5!7! = 792
x(x - y + 1)
.0004809 X 10^11

7. Simplify 4sqrt21 X 5sqrt2 / 10sqrt7
37.5%
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
90 degrees
2sqrt6

8. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
1
12! / 5!7! = 792
A reflection about the origin.
The second graph is less steep.

9. 10^6 has how many zeroes?
The set of output values for a function.
6
Angle/360 x (pi)r^2
Members or elements

10. 25^(1/2) or sqrt. 25 =
C = 2(pi)r
I
x^(4+7) = x^11
5 OR -5

11. (-1)^2 =
A chord is a line segment joining two points on a circle.
180 degrees
1
1/2 times 7/3

12. sqrt 2(sqrt 6)=
Arc length = (n/360) x pi(2r) where n is the number of degrees.
An arc is a portion of a circumference of a circle.
Yes - like radicals can be added/subtracted.
Sqrt 12

13. How many multiples does a given number have?
53 - 59
72
Pi is the ratio of a circle'S circumference to its diameter.
Infinite.

14. Simplify the expression [(b^2 - c^2) / (b - c)]
71 - 73 - 79
Triangles with same measure and same side lengths.
(b + c)
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

15. Solve the quadratic equation ax^2 + bx + c= 0
90pi
Undefined - because we can'T divide by 0.
y = (x + 5)/2
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

16. (-1)^3 =
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
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)
1
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

17. Can the input value of a function have more than one output value (i.e. x: y - y1)?
C = 2(pi)r
1 & 37/132
A circle centered on the origin with radius 8.
No - the input value has exactly one output.

18. Which quandrant is the lower right hand?
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
IV
(n-2) x 180
288 (8 9 4)

19. x^6 / x^3
62.5%
x^(6-3) = x^3
An expression with just one term (-6x - 2a^2)
(b + c)

20. What is the 'Solution' for a set of inequalities.
The overlapping sections.
3
4.25 - 6 - 22
(a - b)(a + b)

21. Order of quadrants:
Yes - like radicals can be added/subtracted.
From northeast - counterclockwise. I - II - III - IV
The union of A and B.
A = I (1 + rt)

22. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
2 & 3/7
A circle centered on the origin with radius 8.
180
C = 2(pi)r

23. How many sides does a hexagon have?
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
6
6 : 1 : 2
Sector area = (n/360) X (pi)r^2

24. 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?
y = 2x^2 - 3
Part = Percent X Whole
(a - b)(a + b)
(b + c)

25. 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
x^(2(4)) =x^8 = (x^4)^2
5 OR -5
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
18

26. The perimeter of a square is 48 inches. The length of its diagonal is:
12sqrt2
2 & 3/7
1
True

27. When the 'a' in the parabola is negative...
The point of intersection of the systems.
4096
The curve opens downward and the vertex is the maximum point on the graph.
2sqrt6

28. Simplify (a^2 + b)^2 - (a^2 - b)^2
Lies opposite the greater angle
Yes - like radicals can be added/subtracted.
4a^2(b)
5

29. Which quadrant is the lower left hand?
A = pi(r^2)
An angle which is supplementary to an interior angle.
$3 -500 in the 9% and $2 -500 in the 7%.
III

30. What is an exterior angle?
500
An angle which is supplementary to an interior angle.
The point of intersection of the systems.
13

31. Define a 'Term' -
Two equal sides and two equal angles.
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)
Angle/360 x 2(pi)r
Angle/360 x (pi)r^2

32. What is the 'Solution' for a system of linear equations?
Ax^2 + bx + c where a -b and c are constants and a /=0
1 & 37/132
Two angles whose sum is 180.
The point of intersection of the systems.

33. How to determine percent increase?
12! / 5!7! = 792
(amount of increase/original price) x 100%
1 & 37/132
8

34. x^(-y)=
18
13
1/(x^y)
A reflection about the axis.

35. 4.809 X 10^7 =
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.
.0004809 X 10^11
1
A tangent is a line that only touches one point on the circumference of a circle.

36. Number of degrees in a triangle
18
180
.0004809 X 10^11
$11 -448

37. 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)
2 & 3/7
4.25 - 6 - 22
1.7
2.592 kg

38. 60 < all primes <70
61 - 67
500
x^(2(4)) =x^8 = (x^4)^2
(a - b)(a + b)

39. Which is greater? 200x^295 or 10x^294?
Its last two digits are divisible by 4.
0
Relationship cannot be determined (what if x is negative?)
Even

40. Define a 'monomial'
An expression with just one term (-6x - 2a^2)
67 - 71 - 73
1.7
Diameter(Pi)

41. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
Undefined - because we can'T divide by 0.
4725
.0004809 X 10^11
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

42. Find the surface area of a cylinder with radius 3 and height 12.
(amount of increase/original price) x 100%
III
90pi
Even

43. 1/2 divided by 3/7 is the same as
Two angles whose sum is 180.
1/2 times 7/3
Even
An expression with just one term (-6x - 2a^2)

44. 5/6 in percent?
62.5%
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
y = (x + 5)/2
83.333%

45. (a^-1)/a^5
27^(-4)
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
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)
1/a^6

46. Formula to calculate arc length?
N! / (n-k)!
Members or elements
Arc length = (n/360) x pi(2r) where n is the number of degrees.
9 : 25

47. 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?
x= (1.2)(.8)lw
No - only like radicals can be added.
A grouping of the members within a set based on a shared characteristic.
48

48. 0^0
IV
Undefined
Arc length = (n/360) x pi(2r) where n is the number of degrees.
Lies opposite the greater angle

49. Convert 0.7% to a fraction.
1
7 / 1000
Its last two digits are divisible by 4.
4725

50. a^0 =
Undefined
5 OR -5
1/(x^y)
1