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robertb answered: 4011 problems
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Radicals/367892: 1 solutions Answer 262248 by robertb(4012)   on 2010-11-08 16:44:30 (Show Source): You can put this solution on YOUR website! , , after squaring both sides. , after transposition and cancellation. , 4 = x-3, after squaring again, or x = 7. This value satisfies the original equation, so this is the final answer.

Expressions-with-variables/367960: Jules's Verne's fictional submarine, the Nautilus, traveled 20,000 leagues under the sea. Let m leagues equal 1 mile. How many mailes dd the Natulis travel? write the problem as an expression 1 solutions Answer 262240 by robertb(4012)   on 2010-11-08 16:37:55 (Show Source): You can put this solution on YOUR website! let x = # of miles. Then 1 mile/m leagues = x/20,000, or , or miles.

Probability-and-statistics/367953: Eight people are entered in a race. If there are no ties, in how many ways can the first two places come out? 1 solutions Answer 262236 by robertb(4012)   on 2010-11-08 16:34:56 (Show Source): You can put this solution on YOUR website! P(8,2) = 8*7 = 56.

Numeric_Fractions/367949: what is 2/3 + (-1/6) please show work 1 solutions Answer 262233 by robertb(4012)   on 2010-11-08 16:33:02 (Show Source): You can put this solution on YOUR website!

Numeric_Fractions/367954: what is -1/2-(-5/8) 1 solutions Answer 262232 by robertb(4012)   on 2010-11-08 16:31:45 (Show Source): You can put this solution on YOUR website!

Numeric_Fractions/367952: what is -5/9-7/18 1 solutions Answer 262231 by robertb(4012)   on 2010-11-08 16:30:40 (Show Source): You can put this solution on YOUR website!

Probability-and-statistics/367569: A new medication for migraine sufferers is known to be successful in 70% of cases. Jessica selects ten migraine sufferers to take part in the testing of the drug. Find the probability that: a) 2 people are cured b) no people are cured 1 solutions Answer 262032 by robertb(4012)   on 2010-11-08 06:10:40 (Show Source): You can put this solution on YOUR website! a) b)

Equations/367593: Solve by factoring 4x^2 - 3x -6 = 0 1 solutions Answer 262030 by robertb(4012)   on 2010-11-08 06:08:19 (Show Source): You can put this solution on YOUR website! It cannot be factored into linear factors having rational coefficients: the discriminant is equal to 105, which is a positive real number but not a perfect square.

Probability-and-statistics/367577: Niall rolls a fair die 50 times. Find: a) the expected number of odd numbers b) the variance of odd numbers c) the standard deviation of odd numbers 1 solutions Answer 262029 by robertb(4012)   on 2010-11-08 06:05:04 (Show Source): You can put this solution on YOUR website! The exercise becomes a binomial experiment with P(odd)= p = 0.5 and P(even) = q= 0.5. a)the expectation is odd numbers. b) the variance is c) the SD is just the square root of (b)--around 3.54.

absolute-value/367597: 6+3│p-4│>12 1 solutions Answer 262027 by robertb(4012)   on 2010-11-08 05:58:48 (Show Source): You can put this solution on YOUR website! 3/p-4/>6, /p-4/>2. This inequality is the same as the pair of inequalities p-4< -2 or p - 4>2, p <2 or p>6. In interval notation, (, 2)U(6, ).

Quadratic_Equations/367622: For what value of k will the roots of 4x^2 + 4x + k be equal? 1 solutions Answer 262023 by robertb(4012)   on 2010-11-08 05:52:32 (Show Source): You can put this solution on YOUR website! The discriminant has to be 0. . This gives 16 = 16k, or k = 1.

Sequences-and-series/367620: The first term of a geometric sequence is 5 and the third term is 7.2.Which of the following can be the fifth term? (A) 8.85 (B) 9.4 (C) 10.368 (D) 11.646 (E) 12.4416 1 solutions Answer 262022 by robertb(4012)   on 2010-11-08 05:50:02 (Show Source): You can put this solution on YOUR website! B) 9.4. the difference between the 1st and 3rd terms is 2.2. Dividing this by 2 gives 1.1, and this is the common difference d. Adding 2.2 to 7.2 gives the 5th term , which is 9.4.

Problems-with-consecutive-odd-even-integers/367616: find two consecutive integers whose sum is 383 1 solutions Answer 262020 by robertb(4012)   on 2010-11-08 05:47:06 (Show Source): You can put this solution on YOUR website! x+x+1 = 383, 2x = 382, x = 191, x+1 = 192

Problems-with-consecutive-odd-even-integers/367618: find two consecutive multiples of 7 whose sum is 84 1 solutions Answer 262017 by robertb(4012)   on 2010-11-08 05:44:49 (Show Source): You can put this solution on YOUR website! 7x + (7x+7) = 84, 14x = 77, 2x = 11. The equation has no integer solution,and thus the problem itself has no solution.

Probability-and-statistics/367615: Let ⌊x ⌋ = the greatest integer that is less than or equal to x. For example ⌊4.23⌋ = 4 and ⌊8⌋ = 8 What is the average of ⌊10.75⌋ and ⌊-3.68⌋ ? 1 solutions Answer 262013 by robertb(4012)   on 2010-11-08 05:38:04 (Show Source): You can put this solution on YOUR website! (10+(-4))/2 = 6/2 = 3

Polynomials-and-rational-expressions/367550: Find the polynomial function that has the given zeros a) 1+ square root 3, 1 – square root 3 b) 0, -2, -3 1 solutions Answer 262012 by robertb(4012)   on 2010-11-08 05:36:05 (Show Source): You can put this solution on YOUR website! a) b)

Equations/367588: Solve this quadratic inequality and show answer in interval notation: 4x^2 - 12x + 9 > 0 1 solutions Answer 262002 by robertb(4012)   on 2010-11-08 02:31:52 (Show Source): You can put this solution on YOUR website! is the same as . All real numbers will satisfy this except x = 3/2, when it is zero. Thus the solution set is (, 3/2)U(3/2, ). 4x^2 - 3x - 6 = 0 Check the discriminant:. The value of the discriminant is positive but is not a perfect square, so the quadratic expression cannot be factored into linear factors with rational coefficients.

Equations/367591: Find the discriminant of this equation and tell if the quadratic equation has 2 real solutions, one real solution, or two imaginary solutions: 9x^2 - 64 = 0 1 solutions Answer 262001 by robertb(4012)   on 2010-11-08 02:28:15 (Show Source): You can put this solution on YOUR website! . Thus there are two distinct real roots.

Quadratic_Equations/367586: Find the value of k so that the equation 3x²-(5+k)x-17=0 will have roots numerically equal but opposite sign.Please answer the question. 1 solutions Answer 262000 by robertb(4012)   on 2010-11-08 02:25:21 (Show Source): You can put this solution on YOUR website! For the roots to be numerically equal but opposite in signs, the factorization of the expression would have to be (ax+b)(ax-b) = , a difference of two squares. This means , and . The middle term has to disappear, and so -(5+k) = 0, or k = -5.

Rational-functions/367578: horizontal asymptote 4x/x-2 1 solutions Answer 261999 by robertb(4012)   on 2010-11-08 02:18:15 (Show Source): You can put this solution on YOUR website! . Dividing 4x by x - 2, we get . As x goes to positive or negative infinity, the expression goes to 4. Thus the horizontal asymptote has equation y = 4.

Triangles/367583: The area of a triangle is 40 and its base is 32. Find the base of a similar triangle whose area is 90. . 1 solutions Answer 261998 by robertb(4012)   on 2010-11-08 02:12:30 (Show Source): You can put this solution on YOUR website! Let k = constant of proportionality between the two similar triangles(bigger-to-smaller.)Then . or k = 3/2. Thus the base of the bigger triangle is .

Human-and-algebraic-language/367580: Can anyone tell me if I did this correctly? The sum of two consecutive integers is 35. This is what I have: x+(x+1)=35 1 solutions Answer 261997 by robertb(4012)   on 2010-11-08 02:04:18 (Show Source): You can put this solution on YOUR website! Yup.

Probability-and-statistics/367510: An instructor gives his class a set of 15 problems with the information that the next quiz will consist of a random selection of 4 of them. If a student has figured out how to do 7 of the problems, what is the probability the he or she will answer correctly at least 3 questions? 1 solutions Answer 261992 by robertb(4012)   on 2010-11-08 00:45:52 (Show Source): You can put this solution on YOUR website! # of ways 3 correct answers: , # of ways 4 correct answers: . # of ways getting 4 questions out of 15: , thus the probability is

Linear-systems/367575: Will you help me solve for y in the equation: 3x-4y=10 1 solutions Answer 261991 by robertb(4012)   on 2010-11-08 00:30:33 (Show Source): You can put this solution on YOUR website! 3x-10 = 4y, so that

Finance/367576: A bottle of perfume contains 10 1/2 ounces and sells for .98 cents. What is the cost per ounce? 1 solutions Answer 261990 by robertb(4012)   on 2010-11-08 00:29:11 (Show Source): You can put this solution on YOUR website! 98 cents/10.5 = 9.33 cents/ounce.

Rectangles/367571: a rectangle is three times as long as it is wide. its perimeter is 36. find each side 1 solutions Answer 261989 by robertb(4012)   on 2010-11-08 00:27:50 (Show Source): You can put this solution on YOUR website! 2(w + 3w) = 36, 2(4w) = 36, 8w = 36, w = 36/8 = 9/2, the width of the rectangle. l = 3w = 27/2, the length of the rectangle.

Miscellaneous_Word_Problems/367507: If, in the ordered pair (a, b), a and b have different signs, then the point (a, b) is ________ in the second quadrant. 1 solutions Answer 261988 by robertb(4012)   on 2010-11-08 00:18:30 (Show Source): You can put this solution on YOUR website! possibly

Sequences-and-series/367543: The first three terms in the binomial expansion of (1+ kx)n are 1− 21x +189x2. Find the value of n and the value of k. Please show all the steps etc... I know the answer, but I don't understand the solution at all... thanks 1 solutions Answer 261987 by robertb(4012)   on 2010-11-08 00:14:52 (Show Source): You can put this solution on YOUR website! The first three terms of the expression are . Hence nk = -21, and , after equating coefficients. The foregoing equation is the same as . Hence by substitution, , or , or 21k = -63, or k = -3. From nk = -21, n = 7.

Exponents-negative-and-fractional/367540: (6x)^-2 1 solutions Answer 261986 by robertb(4012)   on 2010-11-08 00:02:05 (Show Source): You can put this solution on YOUR website!

Polynomials-and-rational-expressions/367516: which numbers cannot be used in place of the variable in the rational expression: 3x/x^2-49 1 solutions Answer 261984 by robertb(4012)   on 2010-11-08 00:00:46 (Show Source): You can put this solution on YOUR website! . So the numbers x = 7 or x = -7 cannot be used into the expression.

Quadratic_Equations/367502: find the vertex, line of symmetry, and maximum/minimum value -2x^2+2x+3 I have tried everything and am completely lost, any help would be appreciated 1 solutions Answer 261983 by robertb(4012)   on 2010-11-07 23:57:56 (Show Source): You can put this solution on YOUR website! The x-coordinate of the vertex is . The y-coordinate of the vertex is . The line of symmetry is x = 1/2, and the maximum value is 7/2.