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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 common monomial factor in the expression 4(c^3)d - (c^2)(d^2) + 2cd?
1
The longest arc between points A and B on a circle'S diameter.
2 & 3/7
Cd

2. A number is divisible by 6 if...
(base*height) / 2
The set of elements which can be found in either A or B.
1 & 37/132
Its divisible by 2 and by 3.

3. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
4:5
90 degrees
2

4. What is the set of elements which can be found in either A or B?
The union of A and B.
x^(4+7) = x^11
Area of the base X height = (pi)hr^2
1/a^6

5. From a box of 12 candles - you are to remove 5. How many different sets of 5 candles could you remove?
12! / 5!7! = 792
18
6
x^(2(4)) =x^8 = (x^4)^2

6. 1:1:sqrt2 is the ratio of the sides of what kind of triangle?
Diameter(Pi)
An isosceles right triangle.
The curve opens upward and the vertex is the minimal point on the graph.
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...

7. Legs 6 - 8. Hypotenuse?
10
Area of the base X height = (pi)hr^2
A chord is a line segment joining two points on a circle.
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)

8. 25^(1/2) or sqrt. 25 =
A central angle is an angle formed by 2 radii.
5 OR -5
1
A set with a number of elements which can be counted.

9. What is the graph of f(x) shifted upward c units or spaces?
(b + c)
The steeper the slope.
F(x) + c
1.7

10. What is the 'Restricted domain of a function'?
When the function is not defined for all real numbers -; only a subset of the real numbers.
1:1:sqrt2
12sqrt2
A set with a number of elements which can be counted.

11. When the 'a' in the parabola is negative...
The curve opens downward and the vertex is the maximum point on the graph.
1
10! / 3!(10-3)! = 120
441000 = 1 10 10 10 21 * 21

12. A cylinder has a surface area of 22pi. If the cylinder has a height of 10 - what is the radius?
1
37.5%
1/a^6
500

13. What is the graph of f(x) shifted left c units or spaces?
A central angle is an angle formed by 2 radii.
F(x + c)
C = 2(pi)r
180 degrees

14. P and r are factors of 100. What is greater - pr or 100?
13pi / 2
Indeterminable.
1.0843 X 10^11
4a^2(b)

15. What is the ratio of the surface area of a cube with an edge of 10 to the surface area of a rectangular solid with dimensions 2 - 4 - and 6?
Two equal sides and two equal angles.
Area of the base X height = (pi)hr^2
90
75:11

16. Can you simplify sqrt72?
Undefined - because we can'T divide by 0.
Factors are few - multiples are many.
A grouping of the members within a set based on a shared characteristic.
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.

17. 20<all primes<30
Members or elements
23 - 29
288 (8 9 4)
180 degrees

18. Simplify (a^2 + b)^2 - (a^2 - b)^2
Yes. [i.e. f(x) = x^2 - 1
4a^2(b)
The two xes after factoring.
3

19. What is the side length of an equilateral triangle with altitude 6?
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...
1
$11 -448
x(x - y + 1)

20. What is a major arc?

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21. Solve the quadratic equation ax^2 + bx + c= 0
(a - b)^2
N! / (n-k)!
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a
1

22. x^(-y)=
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
2
1/(x^y)
62.5%

23. To convert a decimal to a percent...
x= (1.2)(.8)lw
...multiply by 100.
2 & 3/7
Angle/360 x (pi)r^2

24. What are congruent triangles?
3
Triangles with same measure and same side lengths.
A circle centered at -2 - -2 with radius 3.
Use Pythagorean theorem twice. (Once across the surface and then a is the diagonal of surface and b is an edge).

25. Is 0 even or odd?
75:11
Even
72
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)

26. Write 10 -843 X 10^7 in scientific notation
180 degrees
1/(x^y)
1.0843 X 10^11
3 - -3

27. 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?
(amount of decrease/original price) x 100%
N! / (k!)(n-k)!
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
Even

28. What is a tangent?
Triangles with same measure and same side lengths.
Ax^2 + bx + c where a -b and c are constants and a /=0
A tangent is a line that only touches one point on the circumference of a circle.
A reflection about the axis.

29. There are 10 finalists for the school spelling bee. A first - second - and third place trophy will be awarded. How many different people can get the three prizes?
10! / 3!(10-3)! = 120
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.
The union of A and B.

30. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
130pi
1:sqrt3:2
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.
(12/2) x (sqrt15 / sqrt5) = 6sqrt3

31. What is the formula for computing simple interest?
2^9 / 2 = 256
A = I (1 + rt)
The greatest value minus the smallest.
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)

32. What are the rational numbers?
All numbers which can be expressed as a ratio of two integers. (All integers and fractions.) (-2 - 1 - .25 - 1/2)
10! / 3!(10-3)! = 120
Indeterminable.
4a^2(b)

33. 8.84 / 5.2
F(x-c)
F(x + c)
90pi
1.7

34. Formula to find a circle'S circumference from its diameter?
83.333%
(a + b)^2
C = (pi)d
3

35. Formula for the area of a sector of a circle?
3
(b + c)
1 & 37/132
Sector area = (n/360) X (pi)r^2

36. A number is divisible by 3 if ...
130pi
...multiply by 100.
Area of the base X height = (pi)hr^2
The sum of its digits is divisible by 3.

37. How many digits are there between the decimal point and the first even digit in the decimal equivalent of 1/[(2^8)(5^3)]
0
Two angles whose sum is 90.
72
9 & 6/7

38. Which quadrant is the upper right hand?
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
N! / (n-k)!
1/(x^y)
I

39. What is the 'Range' of a series of numbers?
IV
The greatest value minus the smallest.
90pi
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

40. What is the area of a regular hexagon with side 6?
54sqrt3. (divide the hexagon into 6 congruent equilateral triangles.
F(x-c)
The curve opens downward and the vertex is the maximum point on the graph.
4.25 - 6 - 22

41. What is the ratio of the sides of a 30-60-90 triangle?
1:sqrt3:2
The overlapping sections.
71 - 73 - 79
A circle centered on the origin with radius 8.

42. What is the 'domain' of a function?
Expressing a number as the product of a decimal between 1 and 10 - and a power of 10.
The set of input values for a function.
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)
72

43. x^6 / x^3
x^(6-3) = x^3
Infinite.
13
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

44. 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)?
(amount of increase/original price) x 100%
y = (x + 5)/2
31 - 37
(a + b)^2

45. 6w^2 - w - 15 = 0
Two equal sides and two equal angles.
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
3/2 - 5/3
A subset.

46. What is a parabola?
Ax^2 + bx + c where a -b and c are constants and a /=0
x= (1.2)(.8)lw
62.5%
288 (8 9 4)

47. 1/8 in percent?
1.7
When the function is not defined for all real numbers -; only a subset of the real numbers.
12.5%
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)

48. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
[(7+ sqrt93) /2] - [(7 - sqrt93) / 2]
2
A reflection about the axis.
No - the input value has exactly one output.

49. 4.809 X 10^7 =
.0004809 X 10^11
1
0
The second graph is less steep.

50. What is the absolute value function?
G(x) = {x}
37.5%
27^(-4)
The interesection of A and B.