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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. What is the 'Solution' for a system of linear equations?
The point of intersection of the systems.
The sum of digits is divisible by 9.
Angle/360 x 2(pi)r
The two xes after factoring.

2. (-1)^2 =
Even
1
6 : 1 : 2
N! / (k!)(n-k)!

3. Formula to find a circle'S circumference from its radius?
N! / (n-k)!
71 - 73 - 79
C = 2(pi)r
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.

4. A number is divisible by 9 if...
75:11
The sum of digits is divisible by 9.
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
1

5. Can the output value of a function have more than one input value?
288 (8 9 4)
Yes. [i.e. f(x) = x^2 - 1
The longest arc between points A and B on a circle'S diameter.
Even

6. a^2 - b^2
(b + c)
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)
(a - b)(a + b)
Angle/360 x (pi)r^2

7. 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)
6 : 1 : 2
Yes. [i.e. f(x) = x^2 - 1
4.25 - 6 - 22
A = pi(r^2)

8. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
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)
4:5
The sum of its digits is divisible by 3.
(a + b)^2

9. If a=-1 and b=3 - what is the value of (4(a^3)(b^2) - 12(a^2)(b^5)) / (16(a^3)(b^2))?
Triangles with same measure and same side lengths.
12.5%
Cd
20.5

10. 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
When the function is not defined for all real numbers -; only a subset of the real numbers.
Ax^2 + bx + c where a -b and c are constants and a /=0
18
True

11. Number of degrees in a triangle
180
x^(2(4)) =x^8 = (x^4)^2
71 - 73 - 79
The sum of digits is divisible by 9.

12. Circumference of a circle?
1
0
The third side is greater than the difference and less than the sum.
Diameter(Pi)

13. To convert a decimal to a percent...
0
The union of A and B.
The set of input values for a function.
...multiply by 100.

14. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
A reflection about the origin.
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
A circle centered at -2 - -2 with radius 3.
Angle/360 x 2(pi)r

15. What are 'Supplementary angles?'
90
8
Two angles whose sum is 180.
The set of elements which can be found in either A or B.

16. What is the absolute value function?
G(x) = {x}
III
x(x - y + 1)
A = I (1 + rt)

17. What is the graph of f(x) shifted right c units or spaces?
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
F(x-c)
12.5%
72

18. What is the 'Solution' for a set of inequalities.
83.333%
F(x) - c
The overlapping sections.
7 / 1000

19. The perimeter of a square is 48 inches. The length of its diagonal is:
The empty set - denoted by a circle with a diagonal through it.
An expression with just one term (-6x - 2a^2)
48
12sqrt2

20. Factor a^2 + 2ab + b^2
(a + b)^2
(amount of increase/original price) x 100%
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
G(x) = {x}

21. What are the members or elements of a set?
A set with a number of elements which can be counted.
72
The objects within a set.
.0004809 X 10^11

22. 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?
10! / (10-3)! = 720
3/2 - 5/3
62.5%
180 degrees

23. What is the maximum value for the function g(x) = (-2x^2) -1?
1
Diameter(Pi)
3 - -3
10! / 3!(10-3)! = 120

24. In a triangle where the two legs are 4 and 3 - what is the value of a line directly intersecting the middle coming from the meeting point of the two legs?
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)
(base*height) / 2
90 degrees
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

25. Which is greater? 200x^295 or 10x^294?
Relationship cannot be determined (what if x is negative?)
The point of intersection of the systems.
1
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.

26. Legs: 3 - 4. Hypotenuse?
5
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
71 - 73 - 79
1/(x^y)

27. Area of a triangle?
(base*height) / 2
(amount of decrease/original price) x 100%
x^(4+7) = x^11
72

28. To convert a percent to a fraction....
An isosceles right triangle.
(12/2) x (sqrt15 / sqrt5) = 6sqrt3
Divide by 100.
$3 -500 in the 9% and $2 -500 in the 7%.

29. 60 < all primes <70
Its last two digits are divisible by 4.
13pi / 2
1:sqrt3:2
61 - 67

30. Formula to find a circle'S circumference from its diameter?
A reflection about the axis.
C = (pi)d
.0004809 X 10^11
1/(x^y)

31. What are the integers?
2^9 / 2 = 256
All numbers multiples of 1.
A = I (1 + rt)
2sqrt6

32. What is a finite set?
The objects within a set.
A set with a number of elements which can be counted.
(a - b)^2
3

33. sqrt 2(sqrt 6)=
An arc is a portion of a circumference of a circle.
The direction of the inequality is reversed.
Sqrt 12
2(pi)r^2 + 2(pi)rh

34. Convert 0.7% to a fraction.
x^(2(4)) =x^8 = (x^4)^2
The sum of digits is divisible by 9.
7 / 1000
A grouping of the members within a set based on a shared characteristic.

35. Simplify the expression [(b^2 - c^2) / (b - c)]
An angle which is supplementary to an interior angle.
II
(a - b)^2
(b + c)

36. Length of an arc of a circle?
Angle/360 x 2(pi)r
The curve opens downward and the vertex is the maximum point on the graph.
y = 2x^2 - 3
10

37. Can you subtract 3sqrt4 from sqrt4?
x(x - y + 1)
83.333%
Yes - like radicals can be added/subtracted.
10! / (10-3)! = 720

38. Evaluate 3& 2/7 / 1/3
A tangent is a line that only touches one point on the circumference of a circle.
4:5
9 & 6/7
72

39. (6sqrt3) x (2sqrt5) =
Angle/360 x (pi)r^2
Undefined - because we can'T divide by 0.
(6 x 2)(sqrt3 x sqrt5) = 12sqrt15
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

40. P and r are factors of 100. What is greater - pr or 100?
Indeterminable.
A circle centered on the origin with radius 8.
72
(p + q)/5

41. What is the 'domain' of a function?
Move the decimal point to the right x places
The set of input values for a function.
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
1:sqrt3:2

42. What is the ratio of the sides of an isosceles right triangle?
130pi
1:1:sqrt2
Area of the base X height = (pi)hr^2
500

43. Formula of rectangle where l increases by 20% and w decreases by 20%
4.25 - 6 - 22
x= (1.2)(.8)lw
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
A grouping of the members within a set based on a shared characteristic.

44. a^2 + 2ab + b^2
90
The sum of digits is divisible by 9.
Yes - like radicals can be added/subtracted.
(a + b)^2

45. Which is greater? 64^5 or 16^8
9 : 25
53 - 59
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
The empty set - denoted by a circle with a diagonal through it.

46. What is an isoceles triangle?
3/2 - 5/3
From northeast - counterclockwise. I - II - III - IV
Two equal sides and two equal angles.
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

47. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
90
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
...multiply by 100.
12! / 5!7! = 792

48. What is the measure of an exterior angle of a regular pentagon?
72
The overlapping sections.
The curve opens downward and the vertex is the maximum point on the graph.
0

49. 7/8 in percent?
The steeper the slope.
87.5%
1:sqrt3:2
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]

50. Reduce: 4.8 : 0.8 : 1.6
48
Yes. [i.e. f(x) = x^2 - 1
N! / (n-k)!
6 : 1 : 2