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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. Area of a triangle?
180 degrees
(base*height) / 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...
x = [(-b)+/- (sqrt b^2 - 4ac)]/2a

2. sqrt 2(sqrt 6)=
Two equal sides and two equal angles.
The objects within a set.
Sqrt 12
83.333%

3. What is the slope of a horizontal line?
9 & 6/7
4.25 - 6 - 22
0
The graph of 3(x - 1)^2 is a translation (shift) of the graph one unit or space to the right.

4. 6w^2 - w - 15 = 0
The overlapping sections.
3/2 - 5/3
413.03 / 10^4 (move the decimal point 4 places to the left)
Infinite.

5. What is the ratio of the sides of an isosceles right triangle?
1:1:sqrt2
4:5
Area of the base X height = (pi)hr^2
F(x-c)

6. Volume for a cylinder?
Its divisible by 2 and by 3.
Area of the base X height = (pi)hr^2
(a - b)(a + b)
6

7. 8.84 / 5.2
(a + b)^2
A = pi(r^2)
1.7
4725

8. 5/6 in percent?
83.333%
72
A 30-60-90 triangle.
5

9. Define a 'monomial'
1
Sector area = (n/360) X (pi)r^2
A chord is a line segment joining two points on a circle.
An expression with just one term (-6x - 2a^2)

10. How many multiples does a given number have?
(b + c)
Relationship cannot be determined (what if x is negative?)
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
Infinite.

11. 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?
Indeterminable.
Lies opposite the greater angle
0
10! / 3!(10-3)! = 120

12. x^4 + x^7 =
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.
Circumference = Diameter(pi). Use pythagorean theorem to find the diagonal of the square (the diameter).
(b + c)
x^(4+7) = x^11

13. Legs 5 - 12. Hypotenuse?
F(x) + c
13
Lies opposite the greater angle
Yes - like radicals can be added/subtracted.

14. What is an isoceles triangle?
Move the decimal point to the right x places
Two equal sides and two equal angles.
Lies opposite the greater angle
The set of elements found in both A and B.

15. A number is divisible by 9 if...
y = (x + 5)/2
The sum of digits is divisible by 9.
6 : 1 : 2
(n-2) x 180

16. How to determine percent increase?
A reflection about the axis.
500
(amount of increase/original price) x 100%
87.5%

17. For similar triangles - the ratio of their corresponding sides is 2:3. What is the ratio of their areas?
70
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
(a - b)(a + b)
An isosceles right triangle.

18. To convert a percent to a fraction....
3
Divide by 100.
All real numbers which can'T be expressed as a ratio of two integers - positive and negative (pi - -sqrt3)
A 30-60-90 triangle.

19. What is the 'Solution' for a system of linear equations?
10! / (10-3)! = 720
The point of intersection of the systems.
67 - 71 - 73
75:11

20. If 10800 is invested at a simple interest rate of 4% - what is the value of the investment after 18 months?
Yes - because you can factor out a perfect square (36). Sqrt(36 x 2) = sqrt36 X sqrt2 = 6sqrt2.
II
The steeper the slope.
$11 -448

21. In similar hexagons - the ratio of the areas is 16:25. What is the ratio of their corresponding sides?
4:5
A set with a number of elements which can be counted.
It is a function defined by more than one equation - where each equation applies to a different part of the domain of the function.
Sector area = (n/360) X (pi)r^2

22. Define an 'expression'.
500
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)
53 - 59
The set of elements which can be found in either A or B.

23. A brick with dimensions 10. 15 and 25 weighs 1.5 kg. A second brick (same density) has dimensions 12 - 18 - and 30. What is the weight of the second brick?
1/a^6
A chord is a line segment joining two points on a circle.
2.592 kg
(amount of decrease/original price) x 100%

24. 413.03 x 10^(-4) =
413.03 / 10^4 (move the decimal point 4 places to the left)
(a - b)(a + b)
An expression with just one term (-6x - 2a^2)
3sqrt4

25. In a triangle inscribed inside a circle - where the diameter is one side of the triangle - which angle is largest?
Indeterminable.
(p + q)/5
(a - b)^2
The angle intersecting the circumference is always the largest angle - and is always 90 degrees.

26. Can the input value of a function have more than one output value (i.e. x: y - y1)?
48
Undefined
9 & 6/7
No - the input value has exactly one output.

27. 40 < all primes<50
Two angles whose sum is 180.
41 - 43 - 47
16^8 - 64^5 = (4^3)^5 = 4^15 - 16^8=(4^2)^8 = 4^16
An expression with just one term (-6x - 2a^2)

28. 1:sqrt3:2 is the ratio of the sides of what kind of triangle?
A 30-60-90 triangle.
The shortest arc between points A and B on a circle'S diameter.
13pi / 2
1:1:sqrt2

29. What is the formula for computing simple interest?
1:sqrt3:2
(n-2) x 180
A = I (1 + rt)
x= (1.2)(.8)lw

30. The four angles around a point measure y - 2y - 35 and 55 respectively. What is the value of y?
90
An isosceles right triangle.
72
The curve opens downward and the vertex is the maximum point on the graph.

31. What is a minor arc?

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32. What is the measure of an exterior angle of a regular pentagon?
72
0
Part = Percent X Whole
55%

33. What is the graph of f(x) shifted upward c units or spaces?
(a - b)^2
F(x) + c
20.5
500

34. (a^-1)/a^5
F(x-c)
N! / (n-k)!
90 degrees
1/a^6

35. Reduce: 4.8 : 0.8 : 1.6
16.6666%
6 : 1 : 2
2sqrt6
A chord is a line segment joining two points on a circle.

36. If 4500 is invested at a simple interest rate of 6% - what is the value of the investment after 10 months?
The third side is greater than the difference and less than the sum.
4725
.0004809 X 10^11
4.25 - 6 - 22

37. Whats the difference between factors and multiples?
No - the input value has exactly one output.
Factors are few - multiples are many.
The two xes after factoring.
1

38. Legs 6 - 8. Hypotenuse?
9 & 6/7
10
The sum of digits is divisible by 9.
F(x-c)

39. 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.
90 degrees
Triangles with same measure and same side lengths.
(a - b)^2
0

40. Factor a^2 + 2ab + b^2
(a + b)^2
10
A central angle is an angle formed by 2 radii.
Two angles whose sum is 90.

41. What transformation occurs if point C is reflected over the x-axis and then the y-axis?
23 - 29
Its negative reciprocal. (-b/a)
2 & 3/7
A reflection about the axis.

42. Formula of rectangle where l increases by 20% and w decreases by 20%
4:9. The ratio of the areas of two similar triangles equals the square of the ratio of the corresponding sides.
The sum of digits is divisible by 9.
x= (1.2)(.8)lw
1

43. 70 < all primes< 80
Relationship cannot be determined (what if x is negative?)
71 - 73 - 79
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 objects within a set.

44. Simplify (a^2 + b)^2 - (a^2 - b)^2
When we need to avoid having a zero in the denominator or avoid taking the square root of a number.
4a^2(b)
A reflection about the axis.
From northeast - counterclockwise. I - II - III - IV

45. Evaluate (4^3)^2
1
4096
(a + b)^2
6

46. What is the set of elements found in both A and B?
PEMDAS (Parentheses Exponents Multiplication/Division Addition/Subtraction)
(base*height) / 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...
The interesection of A and B.

47. What is the name of set with a number of elements which cannot be counted?
Two angles whose sum is 180.
An infinite set.
2.592 kg
(base*height) / 2

48. 25^(1/2) or sqrt. 25 =
5 OR -5
11 - 13 - 17 - 19
The third side is greater than the difference and less than the sum.
A reflection about the origin.

49. x^6 / x^3
y = (x + 5)/2
The union of A and B.
x^(6-3) = x^3
Divide by 100.

50. What is the 'Solution' for a set of inequalities.
The overlapping sections.
13
...multiply by 100.
Area of the base X height = (pi)hr^2