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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. The larger the absolute value of the slope...
An expression with just one term (-6x - 2a^2)
3 - -3
II
The steeper the slope.

2. (-1)^2 =
(a + b)^2
13
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
1

3. What is the measure of an exterior angle of a regular pentagon?
The direction of the inequality is reversed.
Yes - like radicals can be added/subtracted.
72
The empty set - denoted by a circle with a diagonal through it.

4. What are the integers?
All numbers multiples of 1.
7 / 1000
10! / (10-3)! = 720
A circle centered on the origin with radius 8.

5. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
90pi
A reflection about the origin.
A circle centered at -2 - -2 with radius 3.
7 / 1000

6. What is the formula for computing simple interest?
A = I (1 + rt)
The steeper the slope.
N! / (n-k)!
x= (1.2)(.8)lw

7. What is the area of a regular hexagon with side 6?
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
90 degrees

8. What are the members or elements of a set?
130pi
Cd
F(x + c)
The objects within a set.

9. How many multiples does a given number have?
9 & 6/7
2^9 / 2 = 256
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
Infinite.

10. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
x= (1.2)(.8)lw
8
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
C = 2(pi)r

11. Which is greater? 200x^295 or 10x^294?
83.333%
(p + q)/5
Relationship cannot be determined (what if x is negative?)
Sqrt 12

12. The perimeter of a square is 48 inches. The length of its diagonal is:
The third side is greater than the difference and less than the sum.
0
13
12sqrt2

13. Ratio of ages of Anna and Emma is 3:5 and of Emma and Nicolas is 3:5. What is the ratio of Anna to Nicholas' ages?
When the function is not defined for all real numbers -; only a subset of the real numbers.
9 : 25
$11 -448
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

14. Which is greater? 64^5 or 16^8
A grouping of the members within a set based on a shared characteristic.
10! / (10-3)! = 720
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
Lies opposite the greater angle

15. If 10800 is invested at a simple interest rate of 4% - what is the value of the investment after 18 months?
$11 -448
48
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.
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)

16. A number is divisible by 9 if...
70
A 30-60-90 triangle.
The sum of digits is divisible by 9.
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.

17. 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)
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)
4.25 - 6 - 22
The curve opens upward and the vertex is the minimal point on the graph.
Part = Percent X Whole

18. 3/8 in percent?
1
37.5%
An infinite set.
62.5%

19. (x^2)^4
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
The sum of digits is divisible by 9.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
x^(2(4)) =x^8 = (x^4)^2

20. What is the absolute value function?
6 : 1 : 2
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
500
G(x) = {x}

21. Suppose you have a set of n objects - and you want to select k of them - but the order doesn'T matter. What formula do you use to determine the number of combinations of n objects taken k at a time?
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
N! / (k!)(n-k)!
1
180 degrees

22. To convert a decimal to a percent...
The greatest value minus the smallest.
...multiply by 100.
2
4a^2(b)

23. Legs 5 - 12. Hypotenuse?
Area of the base X height = (pi)hr^2
Cd
13
The curve opens upward and the vertex is the minimal point on the graph.

24. Whats the difference between factors and multiples?
10
A circle centered at -2 - -2 with radius 3.
(amount of decrease/original price) x 100%
Factors are few - multiples are many.

25. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
A reflection about the axis.
The set of elements found in both A and B.
No - the input value has exactly one output.
Indeterminable.

26. What is the 'domain' of a function?
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
4725
The set of input values for a function.
5

27. Formula to calculate arc length?
Arc length = (n/360) x pi(2r) where n is the number of degrees.
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
1
x= (1.2)(.8)lw

28. Which quandrant is the lower right hand?
6
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
IV
83.333%

29. Number of degrees in a triangle
An infinite set.
12sqrt2
(a + b)^2
180

30. 50 < all primes< 60
53 - 59
5
Angle/360 x (pi)r^2
The union of A and B.

31. Simplify (a^2 + b)^2 - (a^2 - b)^2
The set of elements which can be found in either A or B.
4a^2(b)
The point of intersection of the systems.
1

32. 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?
48
The empty set - denoted by a circle with a diagonal through it.
The two xes after factoring.
C = 2(pi)r

33. Surface area for a cylinder?
III
1:sqrt3:2
2(pi)r^2 + 2(pi)rh
G(x) = {x}

34. Which quadrant is the upper right hand?
The overlapping sections.
I
Members or elements
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

35. What is an arc of a circle?
An arc is a portion of a circumference of a circle.
Sector area = (n/360) X (pi)r^2
... the square of the ratios of the corresponding sides.
The set of elements found in both A and B.

36. What is the sum of the angles of a triangle?
180 degrees
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
12sqrt2
(p + q)/5

37. 0^0
Undefined
From northeast - counterclockwise. I - II - III - IV
1
The objects within a set.

38. What is the surface area of a cylinder with radius 5 and height 8?
Two equal sides and two equal angles.
2.592 kg
The interesection of A and B.
130pi

39. What is the 'union' of A and B?
Area of the base X height = (pi)hr^2
No - the input value has exactly one output.
(p + q)/5
The set of elements which can be found in either A or B.

40. What is a chord of a circle?
A tangent is a line that only touches one point on the circumference of a circle.
70
A central angle is an angle formed by 2 radii.
A chord is a line segment joining two points on a circle.

41. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
4725
20.5
G(x) = {x}
.0004809 X 10^11

42. How many digits are there between the decimal point and the first even digit in the decimal equivalent of 1/[(2^8)(5^3)]
F(x) - c
0
Cd
4:5

43. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
A 30-60-90 triangle.
x^(6-3) = x^3
A central angle is an angle formed by 2 radii.
A = pi(r^2)

44. Formula for the area of a circle?
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
I
1.7
A = pi(r^2)

45. 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?
10
The set of elements found in both A and B.
A central angle is an angle formed by 2 radii.
N! / (n-k)!

46. Which quadrant is the upper left hand?
y = (x + 5)/2
A subset.
I
II

47. Hector invested $6000. Part was invested in account with 9% simple annual interest - and the rest in account with 7% simple annual interest. If he earned $490 in the first year of these investments - how much did he invest in each account?
$3 -500 in the 9% and $2 -500 in the 7%.
II
61 - 67
Factors are few - multiples are many.

48. Solve the quadratic equation ax^2 + bx + c= 0
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
Two equal sides and two equal angles.
1.7
C = 2(pi)r

49. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
All numbers multiples of 1.
2^9 / 2 = 256
A reflection about the origin.
Two angles whose sum is 180.

50. a^2 - b^2 =
3/2 - 5/3
The curve opens upward and the vertex is the minimal point on the graph.
6
(a - b)(a + b)