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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. Can you subtract 3sqrt4 from sqrt4?
Yes - like radicals can be added/subtracted.
62.5%
9 & 6/7
The third side is greater than the difference and less than the sum.

2. What is the formula for computing simple interest?
A = I (1 + rt)
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
2.592 kg
12! / 5!7! = 792

3. The slope of a line perpendicular to (a/b)?
(b + c)
Its last two digits are divisible by 4.
Its negative reciprocal. (-b/a)
180 degrees

4. Evaluate 3& 2/7 / 1/3
2sqrt6
The steeper the slope.
Lies opposite the greater angle
9 & 6/7

5. What is the measure of an exterior angle of a regular pentagon?
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).
72
441000 = 1 10 10 10 21 * 21
(a + b)^2

6. Find the surface area of a cylinder with radius 3 and height 12.
The third side is greater than the difference and less than the sum.
90pi
An arc is a portion of a circumference of a circle.
2(pi)r^2 + 2(pi)rh

7. T or F? Given d -e &f =/ 0 - [(d^3)e(f^5)] / 2d(e^3) / [3(d^2)(e^3)(f^7)] / [6(e^5)(f^2)]?
1.0843 X 10^11
True
9 & 6/7
12sqrt2

8. What is the slope of a horizontal line?
3sqrt4
(b + c)
13
0

9. Which is greater? 27^(-4) or 9^(-8)
Infinite.
27^(-4)
x^(2(4)) =x^8 = (x^4)^2
Area of the base X height = (pi)hr^2

10. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
Undefined - because we can'T divide by 0.
A reflection about the origin.
2sqrt6
1.7

11. For what values should the domain be restricted for the function f(x) = sqrt(x + 8)
True
A circle centered at -2 - -2 with radius 3.
8
9 : 25

12. What are the irrational numbers?

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13. x^(-y)=
1/(x^y)
288 (8 9 4)
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)
The point of intersection of the systems.

14. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
The direction of the inequality is reversed.
441000 = 1 10 10 10 21 * 21
4725
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

15. Describe the relationship between the graphs of x^2 and (1/2)x^2
Yes - like radicals can be added/subtracted.
90 degrees
N! / (k!)(n-k)!
The second graph is less steep.

16. 30< all primes<40
G(x) = {x}
III
31 - 37
The union of A and B.

17. Legs: 3 - 4. Hypotenuse?
52
12sqrt2
5
An isosceles right triangle.

18. Evaluate and write as a mixed number: 2/7 - 3/21 + 2 & 4/14
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
2 & 3/7
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)
48

19. Can the output value of a function have more than one input value?
An expression with just one term (-6x - 2a^2)
67 - 71 - 73
2.592 kg
Yes. [i.e. f(x) = x^2 - 1

20. How to determine percent decrease?
An isosceles right triangle.
(amount of decrease/original price) x 100%
No - the input value has exactly one output.
11 - 13 - 17 - 19

21. To multiply a number by 10^x
Move the decimal point to the right x places
Part = Percent X Whole
The union of A and B.
Triangles with same measure and same side lengths.

22. If an inequality is multiplied or divided by a negative number....
x^(2(4)) =x^8 = (x^4)^2
The direction of the inequality is reversed.
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.
Indeterminable.

23. a^0 =
1
A circle centered at -2 - -2 with radius 3.
Move the decimal point to the right x places
90pi

24. Reduce: 4.8 : 0.8 : 1.6
.0004809 X 10^11
2 & 3/7
6 : 1 : 2
130pi

25. What is a finite set?
Cd
...multiply by 100.
75:11
A set with a number of elements which can be counted.

26. What are complementary angles?
A = pi(r^2)
Two angles whose sum is 90.
The second graph is less steep.
48

27. What is the side length of an equilateral triangle with altitude 6?
16.6666%
61 - 67
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...
C = 2(pi)r

28. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
The second graph is less steep.
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
8
2^9 / 2 = 256

29. How many 3-digit positive integers are even and do not contain the digit 4?
288 (8 9 4)
1 & 37/132
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
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.

30. What is the surface area of a cylinder with radius 5 and height 8?
130pi
Divide by 100.
5
Undefined - because we can'T divide by 0.

31. What is the 'domain' of a function?
6
4:5
61 - 67
The set of input values for a function.

32. What is the 'Solution' for a system of linear equations?
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
The point of intersection of the systems.
61 - 67
(a - b)(a + b)

33. 8.84 / 5.2
x^(2(4)) =x^8 = (x^4)^2
x^(6-3) = x^3
1.7
A set with a number of elements which can be counted.

34. Length of an arc of a circle?
A grouping of the members within a set based on a shared characteristic.
Angle/360 x 2(pi)r
x^(6-3) = x^3
(a - b)(a + b)

35. 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.
III
67 - 71 - 73

36. Which quadrant is the upper right hand?
90
I
The sum of digits is divisible by 9.
x^(2(4)) =x^8 = (x^4)^2

37. In a regular polygon with n sides - the formula for the sum of interior angles
(n-2) x 180
10! / (10-3)! = 720
Even
4a^2(b)

38. What are the members or elements of a set?
The objects within a set.
3
The set of elements found in both A and B.
0

39. How to find the area of a sector?
3
An angle which is supplementary to an interior angle.
Angle/360 x (pi)r^2
11 - 13 - 17 - 19

40. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
1.0843 X 10^11
(a - b)(a + b)
A 30-60-90 triangle.
(n-2) x 180

41. What are 'Supplementary angles?'
Its last two digits are divisible by 4.
Two angles whose sum is 180.
3
Two equal sides and two equal angles.

42. Formula of rectangle where l increases by 20% and w decreases by 20%
x= (1.2)(.8)lw
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
The third side is greater than the difference and less than the sum.
F(x-c)

43. How to determine percent increase?
...multiply by 100.
(amount of increase/original price) x 100%
4:5
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

44. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
An arc is a portion of a circumference of a circle.
The overlapping sections.
83.333%
12! / 5!7! = 792

45. What is the third quartile of the following data set: 44 - 58 - 63 - 63 - 68 - 70 - 82
75:11
90
70
87.5%

46. Max and Min lengths for a side of a triangle?
C = 2(pi)r
12sqrt2
The third side is greater than the difference and less than the sum.
F(x-c)

47. What is the coefficient of the x^2 term in the product of (x + 1)(x + 2)(x -1)?
1:sqrt3:2
13pi / 2
2
N! / (k!)(n-k)!

48. What is the area of a regular hexagon with side 6?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Sqrt 12
20.5
6

49. a^2 + 2ab + b^2
x^(6-3) = x^3
61 - 67
31 - 37
(a + b)^2

50. Order of quadrants:
From northeast - counterclockwise. I - II - III - IV
(a - b)(a + b)
C = 2(pi)r
1