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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. 1/8 in percent?
x^(4+7) = x^11
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
12.5%
A grouping of the members within a set based on a shared characteristic.

2. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
53 - 59
18
A reflection about the origin.
28. n = 8 - k = 2. n! / k!(n-k)!

3. 20<all primes<30
500
48
2(pi)r^2 + 2(pi)rh
23 - 29

4. Surface area for a cylinder?
No - only like radicals can be added.
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)
2(pi)r^2 + 2(pi)rh
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.

5. How many multiples does a given number have?
An infinite set.
1/a^6
Infinite.
y = 2x^2 - 3

6. (12sqrt15) / (2sqrt5) =
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
Lies opposite the greater angle
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
2(pi)r^2 + 2(pi)rh

7. x^4 + x^7 =
Even
Yes. [i.e. f(x) = x^2 - 1
x^(4+7) = x^11
(base*height) / 2

8. What is the 'Range' of a series of numbers?
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
Lies opposite the greater angle
The greatest value minus the smallest.
The union of A and B.

9. Solve the quadratic equation ax^2 + bx + c= 0
2
53 - 59
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
The overlapping sections.

10. 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)
Undefined - because we can'T divide by 0.
2
A tangent is a line that only touches one point on the circumference of a circle.
4.25 - 6 - 22

11. How many 3-digit positive integers are even and do not contain the digit 4?
C = (pi)d
288 (8 9 4)
(base*height) / 2
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

12. Formula to find a circle'S circumference from its radius?
C = 2(pi)r
413.03 / 10^4 (move the decimal point 4 places to the left)
A tangent is a line that only touches one point on the circumference of a circle.
Ax^2 + bx + c where a -b and c are constants and a /=0

13. How many sides does a hexagon have?
6
Two angles whose sum is 180.
83.333%
72

14. 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?
Diameter(Pi)
N! / (k!)(n-k)!
A chord is a line segment joining two points on a circle.
5

15. The perimeter of a square is 48 inches. The length of its diagonal is:
A grouping of the members within a set based on a shared characteristic.
12sqrt2
3
Angle/360 x 2(pi)r

16. (x^2)^4
x^(2(4)) =x^8 = (x^4)^2
4:5
True
Triangles with same measure and same side lengths.

17. Which is greater? 200x^295 or 10x^294?
(a + b)^2
Relationship cannot be determined (what if x is negative?)
9 & 6/7
20.5

18. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
An angle which is supplementary to an interior angle.
No - the input value has exactly one output.
12! / 5!7! = 792
When the function is not defined for all real numbers -; only a subset of the real numbers.

19. What is a tangent?
The two xes after factoring.
A tangent is a line that only touches one point on the circumference of a circle.
3 - -3
True

20. 4.809 X 10^7 =
Yes. [i.e. f(x) = x^2 - 1
1.7
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
.0004809 X 10^11

21. What are the roots of the quadrinomial x^2 + 2x + 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
3
Its negative reciprocal. (-b/a)
The two xes after factoring.

22. Convert 0.7% to a fraction.
7 / 1000
3
III
12.5%

23. 1/2 divided by 3/7 is the same as
1:1:sqrt2
(amount of decrease/original price) x 100%
1/2 times 7/3
A grouping of the members within a set based on a shared characteristic.

24. What are complementary angles?
23 - 29
Yes - like radicals can be added/subtracted.
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
Two angles whose sum is 90.

25. 40 < all primes<50
180
An isosceles right triangle.
Factors are few - multiples are many.
41 - 43 - 47

26. Describe the relationship between the graphs of x^2 and (1/2)x^2
10! / (10-3)! = 720
48
The second graph is less steep.
6 : 1 : 2

27. What is the measure of an exterior angle of a regular pentagon?
5 OR -5
Undefined
The sum of its digits is divisible by 3.
72

28. What is the set of elements which can be found in either A or B?
The union of A and B.
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
A circle centered at -2 - -2 with radius 3.
From northeast - counterclockwise. I - II - III - IV

29. Max and Min lengths for a side of a triangle?
The third side is greater than the difference and less than the sum.
x^(4+7) = x^11
4a^2(b)
(n-2) x 180

30. How to determine percent increase?
6
13
(amount of increase/original price) x 100%
288 (8 9 4)

31. Can the output value of a function have more than one input value?
Yes. [i.e. f(x) = x^2 - 1
The empty set - denoted by a circle with a diagonal through it.
Arc length = (n/360) x pi(2r) where n is the number of degrees.
Pi is the ratio of a circle'S circumference to its diameter.

32. 10^6 has how many zeroes?
52
6
1:sqrt3:2
(a - b)^2

33. Write 10 -843 X 10^7 in scientific notation
6
1.0843 X 10^11
2
83.333%

34. Length of an arc of a circle?
Angle/360 x 2(pi)r
2
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...
500

35. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
The set of elements found in both A and B.
(a - b)^2
Undefined
A reflection about the axis.

36. What is the maximum value for the function g(x) = (-2x^2) -1?
1
12.5%
N! / (n-k)!
A circle centered at -2 - -2 with radius 3.

37. 7/8 in percent?
Pi is the ratio of a circle'S circumference to its diameter.
10! / 3!(10-3)! = 120
87.5%
$11 -448

38. What are the smallest three prime numbers greater than 65?
9 & 6/7
67 - 71 - 73
Two angles whose sum is 180.
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)

39. A number is divisible by 4 is...
F(x + c)
Its last two digits are divisible by 4.
Lies opposite the greater angle
N! / (n-k)!

40. Circumference of a circle?
75:11
Diameter(Pi)
IV
The union of A and B.

41. Factor a^2 + 2ab + b^2
1 & 37/132
F(x) + c
(a + b)^2
An arc is a portion of a circumference of a circle.

42. What is a chord of a circle?
37.5%
A chord is a line segment joining two points on a circle.
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
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.

43. 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)]?
10
The interesection of A and B.
True
55%

44. Which is greater? 27^(-4) or 9^(-8)
The shortest arc between points A and B on a circle'S diameter.
27^(-4)
Lies opposite the greater angle
A central angle is an angle formed by 2 radii.

45. If the two sides of a triangle are unequal then the longer side...
Lies opposite the greater angle
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
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
16.6666%

46. There are 10 finalists for the school spelling bee. A first - second - and third place trophy will be awarded. In how many ways can the judges award the 3 prizes?
6
3sqrt4
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
10! / (10-3)! = 720

47. What is the common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
2^9 / 2 = 256
Cd
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
Arc length = (n/360) x pi(2r) where n is the number of degrees.

48. Simplify the expression (p^2 - q^2)/ -5(q - p)
A circle centered on the origin with radius 8.
The set of input values for a function.
(a - b)(a + b)
(p + q)/5

49. What is the sum of the angles of a triangle?
The objects within a set.
180 degrees
Ax^2 + bx + c where a -b and c are constants and a /=0
The greatest value minus the smallest.

50. 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?
70
20.5
Triangles with same measure and same side lengths.
y = 2x^2 - 3