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 Rate-of-work-word-problems/433612: One pipe can fill a tank in 20 minutes, while another takes 30 minutes to fill the same tank. How long would it take the two pipes together to fill the tank?1 solutions Answer 300582 by robertb(4012)   on 2011-04-09 22:33:22 (Show Source): You can put this solution on YOUR website! <==> <==> <==> x = 12 minutes.
 Linear-equations/433606: Find the slope of a line containing (6,5) and (8,-2)1 solutions Answer 300580 by robertb(4012)   on 2011-04-09 22:28:06 (Show Source): You can put this solution on YOUR website!slope = m=
 Polynomials-and-rational-expressions/433594: what does descrates rule of signs tell me about number of real positive zeros and negative real zeros of this function. 5x raised to the 6th-3x raised to the 3rd+x squared-x?1 solutions Answer 300579 by robertb(4012)   on 2011-04-09 22:25:45 (Show Source): You can put this solution on YOUR website!Descartes' rule of signs only gives insight on whether a root is positive or negative, not whether a root is zero. The polynomial has a root of 0. Thus apply Descartes' rule only on . Hence, there might 3 positive roots or 1 positive root. (3 variation of signs.) Considering , (replacing x by -x), we see that there are no negative roots. (No variation of signs.) Hence the original polynomial have 0 as a root, 3 positive roots, and 2 complex roots, OR have 0 as a root, 1 positive root, and 4 complex roots.
 absolute-value/433348: Find the solutions for the equation. 4|6x|+3=23 Use a comma to separate answers as needed.1 solutions Answer 300397 by robertb(4012)   on 2011-04-09 00:48:16 (Show Source): You can put this solution on YOUR website! <==> <==> <==> 6x = 5 , or 6x = -5 ==> x = 5/6, or x = -5/6.
 Linear-equations/433354: Suppose an airplane climbs 15 feet for every 40 feet it moves forward. What is the slope of this airplane's ascent?1 solutions Answer 300396 by robertb(4012)   on 2011-04-09 00:45:17 (Show Source): You can put this solution on YOUR website!, the slope of the airplane's ascent.
 Expressions-with-variables/433355: Factor completely, or state that the polynomial is prime. 1 solutions Answer 300395 by robertb(4012)   on 2011-04-09 00:43:37 (Show Source):
 Inequalities/433306: Prove the following inequality. Then state for which values the LHS equals the RHS. Please show and explain (in simple terms) every step in the solution. a^2 + b^2 >= 2 (a-b-1) Thank you.1 solutions Answer 300360 by robertb(4012)   on 2011-04-08 21:04:55 (Show Source): You can put this solution on YOUR website!I begin with a generally true statement, which is <==> <==> <==> . Equality holds only if a = 1 and b = -1. (This is obvious if you look at the first inequality in this proof.)
 logarithm/433014: Find the domain of f and write it in set builder or interval notation. f(x) = log(4 - √(2-x))1 solutions Answer 300134 by robertb(4012)   on 2011-04-08 07:52:26 (Show Source): You can put this solution on YOUR website!First we must have . <==> after squaring both sides. <==> . Intersect this with , or , to get the interval (-14, 2]. This is the domain.
 logarithm/433015: simplify the expression help. ln ³√e1 solutions Answer 300129 by robertb(4012)   on 2011-04-08 07:39:33 (Show Source):
 logarithm/433018: simplify the expression log(base 8)8^k1 solutions Answer 300128 by robertb(4012)   on 2011-04-08 07:38:23 (Show Source): You can put this solution on YOUR website!. (Or, k is the power to which you should raise 8 to get .)
 Probability-and-statistics/432908: The probability of finding exactly 4 0's in a line 40 digits long is about? The mean number of 0's in a line 40 digits long is?1 solutions Answer 300126 by robertb(4012)   on 2011-04-08 07:35:16 (Show Source): You can put this solution on YOUR website!p = 0.10 and q = 0.90 in a binomial experiment. , to 6 decimal places.
 Probability-and-statistics/432856: Assume the probability of a girl being born is the same as the probability of a boy being born. In a family of four children, find the probability of two boys and two girls.1 solutions Answer 300125 by robertb(4012)   on 2011-04-08 07:28:26 (Show Source):
 Quadratic_Equations/432950: Factor the expression by taking out the greatest common factor. 11a^2 - 55a^3 Please show me the steps to get the answer. Thanks1 solutions Answer 300123 by robertb(4012)   on 2011-04-08 07:24:42 (Show Source):
 test/432964: Show that x^4 +(plus) 4 is prime only for one value of x,where x belongs to set of natural no.s1 solutions Answer 300120 by robertb(4012)   on 2011-04-08 07:17:52 (Show Source): You can put this solution on YOUR website! For all natural numbers , each of the two factors above is a positive integer greater than 1, hence the number itself is composite. If x = 1, the number itself is , which is prime. The solution is complete.
 Exponential-and-logarithmic-functions/432973: 80/(1+15e^-.06x)=50 ; 1 solutions Answer 300119 by robertb(4012)   on 2011-04-08 07:04:06 (Show Source): You can put this solution on YOUR website! <==> <==> <==> <==> <==> x = 53.65, to 2 decimal places.
 test/432980: What is the exact value of sin^(-1)[sin(7pi/6)] ?1 solutions Answer 300118 by robertb(4012)   on 2011-04-08 06:54:16 (Show Source):
 logarithm/432928: log (9x - 24) - log (x-4) = 11 solutions Answer 300117 by robertb(4012)   on 2011-04-08 06:48:10 (Show Source): You can put this solution on YOUR website! <==> <==> ==> 9x - 24 = 10(x-4), assuming . ==> 9x - 24 = 10x - 40 or x = 16. This x-value satisfies the original equation, hence is the final answer.
 Travel_Word_Problems/432926: Ms. Driva Reck drove from her home to a service station at 48 km/h. She returned home by bicycle at 16 km/h. The entire trip took 4 hours. How far was the service station from Ms. Reck's home? 1 solutions Answer 300116 by robertb(4012)   on 2011-04-08 06:42:38 (Show Source): You can put this solution on YOUR website!From the formula D = RT, we get T = D/R, so that letting x = distance from her home to the service station, we get x = 48 kilometers.
 test/432963: The positive integers p,q & r are all prime no.s if p^2-q^2=r,then find all posible values of r?1 solutions Answer 300115 by robertb(4012)   on 2011-04-08 06:37:05 (Show Source): You can put this solution on YOUR website!, where p,q, and r are all prime. Now p and q cannot both be odd primes at the same time, because by then p-q and p+q will both be even, and their product will be even, not prime. (Neither can we assume that p = q = 2. why?) Hence we can assume that q is equal to 2 (the only even prime), whence ==> p - 2 = 1 and p + 2 = r ==> p = 3 and r = 5. OR ==> p - 2 = r and p + 2 = 1 ==> p = -1, which is not acceptable. Thus, the only possible value of r is 5.
 logarithm/432977: Log base 1/4 of 64 log base 1/2 of 81 solutions Answer 300114 by robertb(4012)   on 2011-04-08 06:14:18 (Show Source): You can put this solution on YOUR website!, since , since
 Probability-and-statistics/433000: A national survery showed that 65% of kids hate veies. If 3 kids are chosen from random, what is the probability that all 3 will hate veggies? write as a percent to the nearest tenth1 solutions Answer 300111 by robertb(4012)   on 2011-04-08 05:58:33 (Show Source): You can put this solution on YOUR website!, or 30%, to the nearest tenth.
 Triangles/432942: Find the length of the altitude to the hypotenuse of a right triangle whose sides have lengths 7, 24, and 251 solutions Answer 300082 by robertb(4012)   on 2011-04-07 22:59:34 (Show Source): You can put this solution on YOUR website!By similarity of triangles, ==> ==> , or a = 6.72.
 Proportions/432925: WHAT IS 10% of20% of 250?1 solutions Answer 300081 by robertb(4012)   on 2011-04-07 22:51:51 (Show Source): You can put this solution on YOUR website!0.10*0.20*250 = 5.
 Geometry_Word_Problems/432898: a wheel of one car has a diameter of 20 in, the wheel of another car has a diameter of 24 in. About how many more revolution must the smaller wheel make than the larger wheel to travel 100ft?1 solutions Answer 300080 by robertb(4012)   on 2011-04-07 22:50:21 (Show Source): You can put this solution on YOUR website!The circumference of the bigger wheel = feet. The circumference of the smaller wheel = feet. ==> Revolutions of larger wheel in 100 ft = revolutions. ==> Revolutions of smaller wheel in 100 ft = revolutions. ==> the smaller wheel makes more revolutions than the larger wheel to travel 100ft.
 Quadratic_Equations/432880: Change the quadratic function into vertex form. Then, give the coordinates of the vertex. y = x^2+6x+51 solutions Answer 300079 by robertb(4012)   on 2011-04-07 22:38:45 (Show Source): You can put this solution on YOUR website! <==> <==> ==> Vertex is the point (-3, -4).
 Probability-and-statistics/432909: Ten lines in the table contain 400 digits. The count of 0's in these lines is approximately Normal with a.) mean 40 and standard deviation 36. b.) mean 40 and standard deviation 6. c.) mean 36 and standard deviation 6.1 solutions Answer 300077 by robertb(4012)   on 2011-04-07 22:36:24 (Show Source): You can put this solution on YOUR website! Letter b.
 test/432927: What's the answer, exact value of cot[sin^(-1) (-1/2)] ? I did it but want to make sure I got the right answer! Thanks!1 solutions Answer 300076 by robertb(4012)   on 2011-04-07 22:30:56 (Show Source):