Algebra ->  Tutoring on algebra.com -> See tutors' answers!      Log On

 Tutoring Home For Students Tools for Tutors Our Tutors Register Recently Solved
 By Tutor
| By Problem Number |

Tutor:

Recent problems solved by 'drk'

Jump to solutions: 0..29 , 30..59 , 60..89 , 90..119 , 120..149 , 150..179 , 180..209 , 210..239 , 240..269 , 270..299 , 300..329 , 330..359 , 360..389 , 390..419 , 420..449 , 450..479 , 480..509 , 510..539 , 540..569 , 570..599 , 600..629 , 630..659 , 660..689 , 690..719 , 720..749 , 750..779 , 780..809 , 810..839 , 840..869 , 870..899 , 900..929 , 930..959 , 960..989 , 990..1019 , 1020..1049 , 1050..1079 , 1080..1109 , 1110..1139 , 1140..1169 , 1170..1199 , 1200..1229 , 1230..1259 , 1260..1289 , 1290..1319 , 1320..1349 , 1350..1379 , 1380..1409 , 1410..1439 , 1440..1469 , 1470..1499 , 1500..1529 , 1530..1559 , 1560..1589 , 1590..1619 , 1620..1649 , 1650..1679 , 1680..1709 , 1710..1739 , 1740..1769 , 1770..1799 , 1800..1829 , 1830..1859 , 1860..1889 , 1890..1919, >>Next

 Expressions-with-variables/266681: Solve ax - 3x + 5 = a + b for x. State any restrictions on the variables.1 solutions Answer 195918 by drk(1908)   on 2010-02-07 14:50:10 (Show Source): You can put this solution on YOUR website!here is our original equation (i) step 1 - subtract 5 to get (ii) step 2 - take out the gcf to get (iii) step 3 - divide by a-3 to get (iv) restrictions: a cannot = 3
 Exponential-and-logarithmic-functions/266682: How would you sold this equation: f(x) divided by g(x) f(x) = 4x^2 (four x to the second power); g(x) = -3x^ 4/3 (negative 3x to the four thirds power)1 solutions Answer 195917 by drk(1908)   on 2010-02-07 14:46:55 (Show Source): You can put this solution on YOUR website! we simplify the fraction as (-4/3) and then use the division rule, subtract exponents, to get x^(2/3) together the answer is
 test/266675: the derivative of (4x)^3(2x)^6 is?1 solutions Answer 195916 by drk(1908)   on 2010-02-07 14:44:21 (Show Source): You can put this solution on YOUR website!We will rewrite this as or now the derivative is
 test/266674: the equation of a tangent line to the curve x^2+y^2=169 at the point (5,-12) is?1 solutions Answer 195914 by drk(1908)   on 2010-02-07 14:39:54 (Show Source): You can put this solution on YOUR website!step 1 - we take a derivative of both sides and get step 2 - solve for dy/dx step 3 - put your coordinates in and get --- so, the slope is dy/dx = m = 5/12 --- step 4 - using slope and our coordinate as well as y = mx + b, we get and then solving for b, we get --- step 5 - final equation is
 Geometry_Word_Problems/266668: You have 700 feet of fencing to enclose a rectangular field. Express the area of the field, A, as a function of one of its dimensions, x.1 solutions Answer 195913 by drk(1908)   on 2010-02-07 14:32:47 (Show Source): You can put this solution on YOUR website!The perimeter is expressed as (i) or (ii) dividing by 2 we get (iii) solve for y as (iv) --- area formula is (v) substituting (iv) into (v) we get (vi)
 Length-and-distance/266670: Find the coordinates of the other endpoint of the segment, given its midpoint and one endpoint. Midpoint (8,0), endpoint (3,2) The other endpoint is......? (must have ordered pair)1 solutions Answer 195912 by drk(1908)   on 2010-02-07 14:30:15 (Show Source): You can put this solution on YOUR website!Line them up like this endpoint: (3,2) midpoint: (8,0) endpoint: to find the endpoint coordinates, look at the x's. 3 to 8 means add 5. add 5 more and we get 13 look at the y's. 2 to 0 means subtract 2. subtract 2 more and we get -2. The other endpoint is (13,-2)
 Trigonometry-basics/266671: SKATEBOARDING The angle that a skateboarding ramp forms with the ground is 25 degrees and the height of the ramp is 6 feet. Determine the length of the ramp.1 solutions Answer 195910 by drk(1908)   on 2010-02-07 14:27:47 (Show Source): You can put this solution on YOUR website!draw a right triangle and place 25 degrees at a bottom vertex in this case we have the opposite side and want the hypotenuse. This means we need sine theta. sin 25 = 6/r r = 6/sin(25) ~ 14.2 feet
 Linear-systems/266669: F=(GMm)/d2 ;for d21 solutions Answer 195909 by drk(1908)   on 2010-02-07 14:25:27 (Show Source): You can put this solution on YOUR website!here s the original question solve the following formula: F=(GMm)/d2 for d2 ---- step 1 cross multiply to get step 2 - divide by F to get
 Surface-area/266666: 1.What is the surface area that has a diameter of 3 inches and height of 5 inches? 2.What is the total square feet of a rectangle that is 12 ft x 8ft x11ft? 3.A rectangular swimming pool has a length of 18 ft, width of 10 ft, and a depth of 4ft. What is the volume of water the pool can hold?1 solutions Answer 195907 by drk(1908)   on 2010-02-07 14:23:33 (Show Source): You can put this solution on YOUR website!1.What is the surface area that has a diameter of 3 inches and height of 5 inches? the diameter = 3, so radius = 1.5 so or --- 2.What is the total square feet of a rectangle that is 12 ft x 8ft x11ft? we get then or --- 3.A rectangular swimming pool has a length of 18 ft, width of 10 ft, and a depth of 4ft. What is the volume of water the pool can hold? or which is cu. ft.
 test/266664: if x+y=xy, then dy/dx is?1 solutions Answer 195904 by drk(1908)   on 2010-02-07 14:16:56 (Show Source): You can put this solution on YOUR website!We use implicit differentiation here. On the left, it is regular derivatives, but on the right we need to the product rule. we get (i) step 1 - subtract 1 (dy/dx) from both sides and then subtract y from both sides to get (ii) step 2 - factor out the dy/dx to get (iii) step 3 - divide by x-1 to get (iv)
 Surface-area/266652: Suppose the volume must be 50in^3, What are the values for r and h that will minimize the amount of sheet metal required to obtain this volume. I know volume is v= (pi)r^2h. I also know the surface area is sa= 2(pi)rh+2(pi)r^2. I have been working on this all day. Any help would be greatly appreciated. Thanks1 solutions Answer 195898 by drk(1908)   on 2010-02-07 13:57:40 (Show Source): You can put this solution on YOUR website!lets start with (i) we know v = 50, so we get (ii) If we solve for h, we get (iii) now we look at surface area as (iv) substitute (iii) into (iv) to get (v) now everything is in terms of r. getting a common denominator as pir^2, we get (vi) now, factoring, we get (vii) reducing we get (viii) It turns out that r is minimum at 2. This means that h = 50/4pi or h ~ 3.97887 This gives us a minimum sa at sa = 75.1326
 Linear-systems/266646: Not sure if I am doing this correctly: 8(y+3)=3(2y+12) 8y+24=6y+36 2y+24=121 solutions Answer 195895 by drk(1908)   on 2010-02-07 13:41:55 (Show Source): You can put this solution on YOUR website!You are good at next subtract 24 to get subtract 6y to get divide to get
 Linear-equations/266648: I need to find the solution for 0.8x<-401 solutions Answer 195893 by drk(1908)   on 2010-02-07 13:38:50 (Show Source): You can put this solution on YOUR website!divide both sides by 0.8 to get x < -50
 Linear-equations/266649: I need to solve 8x-(3x+4)=61 solutions Answer 195892 by drk(1908)   on 2010-02-07 13:37:53 (Show Source): You can put this solution on YOUR website!here is the problem (i) step 1 - distribute the (-) to get (ii) step 2 -combine like terms to get (iii) step 3 - add 4 to get (iv) divide by 5 to get (v)
 Linear-systems/266647: please this the last time i am asking for help. solve for x and y. during a techno-geek-store sale 6 blank video tapes and 12 blank dvd's cost \$35.10.during the same sale, 8 blank video tapes and 3 blank dvd's cost \$27.95. what was the cost of a blank video tape and the cost of a blank dvd? please!please!please!help me!!!1 solutions Answer 195891 by drk(1908)   on 2010-02-07 13:35:57 (Show Source): You can put this solution on YOUR website!Let v = video and d = dvd --- from the given we get (i) (ii) step 1 - multiply (ii) by -4 to get (iii) step 2 - add (ii) and (iii) to get (iv) divide by -26 to get (v) and then (vi)
 Geometry_Word_Problems/266645: a triangle is 10cm wider that it is tall, the area is 28cm squared. find the height and base1 solutions Answer 195889 by drk(1908)   on 2010-02-07 13:31:42 (Show Source): You can put this solution on YOUR website!Let the height = h. base = h + 10 area = 28 --- The area of a triangle has the formula --- from the given information, we get multiply both sides by 2 to get distribute to get set = 0 to get factor to get solving we get h = -14 and h = 4 we can't use the -14, so our only answer is h = 4 cm
 Polynomials-and-rational-expressions/266642: 18x^3-36x^2-38x-4 / 6x+41 solutions Answer 195888 by drk(1908)   on 2010-02-07 13:28:09 (Show Source): You can put this solution on YOUR website!We can solve this by polynomial or synthetic division. Synthetic is faster. First, set 6x + 4 = 0 and solve for x as x = -2/3. Now divide as (-2/3) // . . . . . . . . 18 . . . . . . -36. . . . . . -38 . . . . . . . -4 . . . . . . . . . . . . . . . . . . . . . . . . -12 . . . . . . 32 . . . . . . . . 4 . . . . . . . . . . . . . . . .18. . . . . . . -48. . . . . . .-6. . . . . . . . .0 --- we know one root is x = (-2/3) we have 18x^2 - 48x - 6 = 0 divide by 6 to get 3x^2 - 8x - 1 = 0 using the quadratic, we get x ~ 2.786 and x ~ -0.1196 so, our 3 roots are {-2/3, -.1196, and 2.786}
 Graphs/266639: Solve by graphing. y = 3x - 5 y = 2x + 101 solutions Answer 195887 by drk(1908)   on 2010-02-07 13:21:49 (Show Source): You can put this solution on YOUR website!The solution is (15, 40) Here is the graph
 Graphs/266640: Solve by graphing. y = 4x + 80 y = (1/2)x +101 solutions Answer 195886 by drk(1908)   on 2010-02-07 13:19:45 (Show Source): You can put this solution on YOUR website!The solution should be (-20,0) Here is the graph
 Mixture_Word_Problems/266638: how much water must be evaporated from 32 ounces of a 4% salt solution to make a 6% slat solution?1 solutions Answer 195885 by drk(1908)   on 2010-02-07 13:15:03 (Show Source): You can put this solution on YOUR website!this is a mixture problem. Here is a table based on the given information solutions . . . . . . . % . . . . . . . . ounces . . . . . . . . . .%ounces salt . . . . . . . . . . .4 . . . . . . . . .32 . . . . . . . . . . . . . . .128 water . . . . . . . . .0 . . . . . . . . . x . . . . . . . . . . . . . . . .0 mixture. . . . . . . 6 . . . . . . . . . x + 12. . . . . . . . . . . . 6x + 72 looking at the third column, we have subtract 72 to get dividing, we get
 absolute-value/266637: Can you give me an example of an absolute value equation that has only one possible solution?1 solutions Answer 195883 by drk(1908)   on 2010-02-07 13:08:44 (Show Source): You can put this solution on YOUR website! --- the only answer is 5. --- In general, we have
 Linear-systems/266590: please help me solve for x and y it takes bob the boy scout 10 hours to paddle upstream {against the current} a distance 15 miles. when he turns around he finds it only takes him 5 hour to paddle 22.5 miles with the current.how fast is bob's boat going in stilll water and what is the speed of the curent of the river? please solve this problem right now!!!! thank you1 solutions Answer 195882 by drk(1908)   on 2010-02-07 13:06:36 (Show Source): You can put this solution on YOUR website!This is a RTD problem. Here is a table based on given information paddle . . . . . . . . .rate . . . . . . . . . time . . . . . . . . . distance up stream . . . . . .r - c . . . . . . . . . . .10 . . . . . . . . . . 10r - 10c =15 down stream . . . .r + c . . . . . . . . . . .5 . . . . . . . . . . .5r + 5c = 22.5 totals . . . . . . . . . Looking at column 3 we get (i) 10r - 10c = 15 (ii) 5r + 5c = 22.5 multiply (ii) by 2 to get (iii) 10r + 10c = 45 add (i) and (iii) to get (iv) 15r = 60 divide to get (v) r = 4 This means that the current is c = 2.5
 Trigonometry-basics/266599: show that f(x)=(x-2)/(x+3) is invertible by finding its inverse. (a) what is the domain of f(x)? the range of f-1(x)? (b) what is the domain of f-(x)? the range of f(x)?1 solutions Answer 195872 by drk(1908)   on 2010-02-07 11:44:32 (Show Source): You can put this solution on YOUR website!Here is the original equation (i) to find the inverse switch the x and y parts. (ii) cross multiply to get (iii) add 2 and then subtract xy to get (iv) factor out the y to get (v) divide by 1-x to get (vi) this is the inverse ---- a). domain of f(x) is all reals except x = -3 The range of f^(-1)(x) is all reals except y = -3 b). The range of f(x) is all reals except y = 1 the domain of f^(-1)(x) is all reals except x = 1
 Complex_Numbers/266600: how to solve with Given that (x+iy)/(2-i) , find x and y.1 solutions Answer 195871 by drk(1908)   on 2010-02-07 11:38:41 (Show Source): You can put this solution on YOUR website!we are given (i) step 1 - multiply by the conjugate of (2-i) which is (2+i) to get (ii) and simplified, we get (iii) we then separate our real and imaginary parts to get (iv) + --- at this point there is no equal sign, so we can't solve for x and y, just rewrite using x and y in the real and imaginary parts.
 Circles/266569: if a trampoline has a radius of 6.5 feet how much fencing is needed to go around the circumference1 solutions Answer 195867 by drk(1908)   on 2010-02-07 10:31:36 (Show Source): You can put this solution on YOUR website!WE need the circumference formula which is we know r = 6.5, so we have {{C = 2*pi*6.5}}} or feet
 Equations/266557: Solve for the literal equation of X. 13(x+2g) - 3(4x+5g) = 01 solutions Answer 195866 by drk(1908)   on 2010-02-07 10:28:26 (Show Source): You can put this solution on YOUR website!here is the original equation (i) step 1 - distribute the 13 and the -3 to get (ii) step 2- combine like terms to get (iii) step 3 - solve for x to get (iv)
 Distributive-associative-commutative-properties/266564: when you look at a commutative and associative properties in algbra what is the difference between the two1 solutions Answer 195864 by drk(1908)   on 2010-02-07 10:25:56 (Show Source): You can put this solution on YOUR website!Commutative property is expressed as a + b = b+ a OR a x b = b x a The idea is that we are reversing our information. ---- Associative property is expressed as (a + b) + c = a + (b + c) OR (a x b) x c = a x (b x c) The order is the same, only parenthesis have shifted. ----- that is the main difference.
 Equations/266561: Solve for the literal equation of X. ax/6 = 2b1 solutions Answer 195862 by drk(1908)   on 2010-02-07 10:23:39 (Show Source): You can put this solution on YOUR website!Here is the original equation (i) step 1 - multiply both sides by (6/a) to get (ii)
 Circles/266562: an ice cream cone has a radius of 2cm and a height of 7cm,what is the volume?1 solutions Answer 195861 by drk(1908)   on 2010-02-07 10:22:17 (Show Source): You can put this solution on YOUR website!The volume of a cone is (i) where B = area of base (circle) and h = height. from (i) we could say (ii) Now from above, we get (iii) or (iv)
 Graphs/266560: Solve by the substitution method 6m+n=23 m-6n=10 the solution is1 solutions Answer 195858 by drk(1908)   on 2010-02-07 10:19:14 (Show Source): You can put this solution on YOUR website!here is the original system: (i) (ii) since we must use substitution, we can solve (i) for n and get (iii) substitute (iii) into (ii) to get (iv) distribute and simplify to get (v) combine like terms to get (vi) add 138 to get (vii) divide by 37 to get (viii) now, So, we get (4,-1)