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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. A number is divisible by 4 is...
Two equal sides and two equal angles.
4725
6
Its last two digits are divisible by 4.

2. What is the name of set with a number of elements which cannot be counted?
Indeterminable.
6
An infinite set.
Sector area = (n/360) X (pi)r^2

3. Surface area for a cylinder?
0
2(pi)r^2 + 2(pi)rh
7 / 1000
Two equal sides and two equal angles.

4. 2sqrt4 + sqrt4 =
Undefined - because we can'T divide by 0.
A = I (1 + rt)
3sqrt4
53 - 59

5. 7/8 in percent?
6
0
87.5%
(a + b)^2

6. Max and Min lengths for a side of a triangle?
The set of input values for a function.
62.5%
The third side is greater than the difference and less than the sum.
Indeterminable.

7. 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?
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
A circle centered on the origin with radius 8.
72
Lies opposite the greater angle

8. What is an isoceles triangle?
The set of elements which can be found in either A or B.
$11 -448
Two equal sides and two equal angles.
From northeast - counterclockwise. I - II - III - IV

9. What is a chord of a circle?
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
A chord is a line segment joining two points on a circle.
The sum of digits is divisible by 9.
When the function is not defined for all real numbers -; only a subset of the real numbers.

10. (-1)^2 =
No - only like radicals can be added.
1
7 / 1000
41 - 43 - 47

11. Solve the quadratic equation ax^2 + bx + c= 0
9 & 6/7
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
(b + c)
N! / (n-k)!

12. 5/8 in percent?
20.5
62.5%
(p + q)/5
Relationship cannot be determined (what if x is negative?)

13. 5x^2 - 35x -55 = 0
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
9 & 6/7
The union of A and B.
All numbers multiples of 1.

14. 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)
4.25 - 6 - 22
2^9 / 2 = 256
5
4096

15. Reduce: 4.8 : 0.8 : 1.6
1
I
41 - 43 - 47
6 : 1 : 2

16. Can you subtract 3sqrt4 from sqrt4?
Triangles with same measure and same side lengths.
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
Yes - like radicals can be added/subtracted.
$3 -500 in the 9% and $2 -500 in the 7%.

17. When the 'a' in a parabola is positive....
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
The curve opens upward and the vertex is the minimal point on the graph.
Yes. [i.e. f(x) = x^2 - 1
Relationship cannot be determined (what if x is negative?)

18. 20<all primes<30
All numbers multiples of 1.
23 - 29
Angle/360 x (pi)r^2
x= (1.2)(.8)lw

19. What is it called when a point is reflected to the quadrant opposite it (i.e. I to III or II to IV)?
A reflection about the origin.
90pi
9 : 25
Two equal sides and two equal angles.

20. Can you simplify sqrt72?
13
G(x) = {x}
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.

21. How to find the circumference of a circle which circumscribes a square?
The set of input values for a function.
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
Part = Percent X Whole

22. Simplify the expression (p^2 - q^2)/ -5(q - p)
(p + q)/5
31 - 37
A set with a number of elements which can be counted.
62.5%

23. Suppose that the graph of f(x) is the result of stretching y=x + 5 away from the x-axis by a factor of 2. What is the new equation for the graph f(x)?
y = (x + 5)/2
27^(-4)
1:1:sqrt2
F(x) - c

24. The number of degrees in the largest angle of a triangle inscribed in a circle - in which the diameter of the circle is one side of the triangle.
1
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
10! / (10-3)! = 720
90 degrees

25. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
The steeper the slope.
(amount of decrease/original price) x 100%
4:5
67 - 71 - 73

26. Which quadrant is the lower left hand?
III
Infinite.
67 - 71 - 73
90 degrees

27. What is the percent formula?
Two angles whose sum is 180.
Part = Percent X Whole
130pi
180 degrees

28. Legs 6 - 8. Hypotenuse?
6
10
F(x) - c
Its last two digits are divisible by 4.

29. 1/2 divided by 3/7 is the same as
1/2 times 7/3
... the square of the ratios of the corresponding sides.
F(x) + c
18

30. What is an exterior angle?
An angle which is supplementary to an interior angle.
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
Diameter(Pi)
(a + b)^2

31. Formula to find a circle'S circumference from its radius?
The longest arc between points A and B on a circle'S diameter.
C = 2(pi)r
A tangent is a line that only touches one point on the circumference of a circle.
The set of elements which can be found in either A or B.

32. What does the graph (x+2)^2 + (y+2)^2 = 9 look like?
x^(6-3) = x^3
N! / (n-k)!
x^(4+7) = x^11
A circle centered at -2 - -2 with radius 3.

33. Nine coins are tossed simultaneously. In how many of the outcomes will the fourth coin tossed show heads?
2^9 / 2 = 256
4096
1/(x^y)
(a - b)(a + b)

34. Is 0 even or odd?
Even
(p + q)/5
The interesection of A and B.
0

35. What is the 'Range' of a function?
The set of output values for a function.
(base*height) / 2
(a + b)^2
An expression with just one term (-6x - 2a^2)

36. Formula of rectangle where l increases by 20% and w decreases by 20%
x= (1.2)(.8)lw
Sqrt 12
A tangent is a line that only touches one point on the circumference of a circle.
G(x) = {x}

37. 200 <_ x <_ 300. How many values of x are divisible by 5 & 8?
3
(base*height) / 2
An infinite set.
The point of intersection of the systems.

38. If 8 schools are in a conference - how many games are played if each team plays each other exactly once?
12! / 5!7! = 792
(a - b)(a + b)
28. n = 8 - k = 2. n! / k!(n-k)!
10

39. If the two sides of a triangle are unequal then the longer side...
Lies opposite the greater angle
52
Part = Percent X Whole
(p + q)/5

40. To multiply a number by 10^x
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
Move the decimal point to the right x places
130pi
2sqrt6

41. 8.84 / 5.2
The union of A and B.
1.7
The set of output values for a function.
288 (8 9 4)

42. What is the set of elements found in both A and B?
The interesection of A and B.
F(x-c)
A reflection about the axis.
2^9 / 2 = 256

43. What is the 'domain' of a function?
A set with no members - denoted by a circle with a diagonal through it.
The second graph is less steep.
The set of input values for a function.
The sum of its digits is divisible by 3.

44. What is the 'Range' of a series of numbers?
11 - 13 - 17 - 19
130pi
(a - b)(a + b)
The greatest value minus the smallest.

45. 1/8 in percent?
9 & 6/7
Cd
90pi
12.5%

46. What is the graph of f(x) shifted upward c units or spaces?
90 degrees
(a + b)^2
F(x) + c
Even

47. 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
A reflection about the origin.
1
A chord is a line segment joining two points on a circle.

48. What are congruent triangles?
Triangles with same measure and same side lengths.
441000 = 1 10 10 10 21 * 21
3
180 degrees

49. What is the 'Restricted domain of a function'?
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
When the function is not defined for all real numbers -; only a subset of the real numbers.
(base*height) / 2
A subset.

50. a^0 =
2.592 kg
A = I (1 + rt)
1
1/(x^y)