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 'oberobic'

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 , 1920..1949 , 1950..1979 , 1980..2009 , 2010..2039 , 2040..2069 , 2070..2099 , 2100..2129 , 2130..2159 , 2160..2189 , 2190..2219 , 2220..2249 , 2250..2279 , 2280..2309

 Rate-of-work-word-problems/100651: A group of 10 6- and 12- voltbatteries are wired in series as shown at the right. the sum of their voltages is 84 volts. How many of each type of battery are used?1 solutions Answer 73291 by oberobic(2304)   on 2007-09-26 19:49:04 (Show Source): You can put this solution on YOUR website!We have 10 batteries, so let's say the number of 6V batteries is x. That means the number of 12V batteries is 10 - x. And we're told that 6x + 12(10-x) = 84 volts. 6x is the 6 volts per battery times x, which is the number of 6V batteries. Likewise 12(10-x) is the 12 volts per battery times the number of 12V batteries. So, we have 6x + 120 - 12x = 84. Combining the x terms we have -6x + 120 = 84. Subtracting 120 from both sides, we have -6x = -36. Dividing by -6, we have x = 6. That means the number of 6V batteries is 6, and the number of 12V batteries is 10-6=4. ALWAYS check! 6*6=36 and 4*12=48, 36+48=84. Check.
 Square-cubic-other-roots/100669: Solve the equations. check the solutions. sqrt(4x+1+3)=01 solutions Answer 73278 by oberobic(2304)   on 2007-09-26 19:24:37 (Show Source): You can put this solution on YOUR website!Squaring both sides, we have 4x + 1 + 3 = 0. Simplifying, 4x = -4, which means x = -1.
 Inequalities/100674: I have two word problems that I really need help on. 1)Two cars leave Denver at the same time and travel in opposite directions. One car travels 15mi/h faster than the other car. The cars are 460mi apart in 4 hours. How fast is each car traveling? 2)A club decides to sell T-shirts for \$12 as a fund-raiser. It costs \$20 plus \$8 per T-shirt to make the T-shirts. How many T-shirts does the club need to make and sell in order to earn \$100? I was wonder how can we contact the tutors to thank them for helping us? 1 solutions Answer 73272 by oberobic(2304)   on 2007-09-26 19:11:30 (Show Source): You can put this solution on YOUR website!1) Problems like this build on the fact that something has to equal something else. In this case, we know they both traveled for 4 hours. The distance equation is d = r * r, so for Car1 d1 = r*4 and for Car2 d2 = (r+15)*4. And we know that d1 + d2 = 460 miles (the distance they are apart after 4 hours). Substituting, we have 4r + 4r + 60 = 460. That simplifies to 8r = 400, so r = 50. That means r+15 is 65. Car1 traveling at 50 and Car2 is traveling at 65. ALWAYS check your answer. 4*50 = 200 miles. 4*65 = 260. 200+260=460. Check. 2) Total Revenue = \$12 times the number of shirts sold (call that x). Total Cost is \$20 plus \$8 * x. Profit is total revenue minus total cost. So, we now have some linear equations to solve, with only one variable. , which is the total revenue. , which is the total cost. , which is the desired profit. , which is the standard profit equation. Therefore, by substituting what we know: . Simplifying, we have: , so . ALWAYS check your answer! So TR = 30*\$12 = \$360; TC = 20 + \$8*30 = \$260; which means P = 360 - 260 = 100. Check.
 Systems-of-equations/100660: Write and solve an equation to find the value of x. 4.8 , 1.6 , 5.2, x ; mean 3.71 solutions Answer 73256 by oberobic(2304)   on 2007-09-26 18:37:26 (Show Source): You can put this solution on YOUR website!The mean is the sum of the values divided by the count of the number of values. The sum of the values is 4.8 + 1.6 + 5.2 + x. The number of values equals 4. Thus we know that Multiplying by 4, we have Subtracting 13.6 from both sides, we have the answer We now check our answer by substituting the value of x into the original equation and solve it, to make sure the mean is 3.7. . Check.
 Linear-equations/100486: Solve by substitution. 38.) 10x + 2y = 7 y = -5x +3 1 solutions Answer 73166 by oberobic(2304)   on 2007-09-25 23:12:27 (Show Source): You can put this solution on YOUR website!Substituting for y, 10x + 2(-5x + 3) = 7. That simplifies to 10x - 10x + 6 = 7, or 6 = 7. That is not possible, so there is no solution for the simultaneous equations. One or the other of the equations is false.
 decimal-numbers/100485: in a bottling company a machine can fill a 2 liter bottle in 0.5 seconds and move the next bottle into place in 0.1 seconds. how many 2 liter bottles can be filled by the machine in 2 h? or 2 hours? 1 solutions Answer 73164 by oberobic(2304)   on 2007-09-25 23:04:43 (Show Source): You can put this solution on YOUR website!It takes .6 sec to fill a bottle and move the next one into place to be filled. In one hour (3600 sec), the machine can fill 6000 bottles (that is 3600/.6). In two hours, it can fill 12000.
 Graphs/100359: This question is from textbook texas algebra 2 how do you write and graph an equation for (A LINE PASSING) through (-2,1) and parallel to y=-2/3x-41 solutions Answer 73162 by oberobic(2304)   on 2007-09-25 22:58:31 (Show Source): You can put this solution on YOUR website!Parallel lines have the same slope (by definition), so the slope of the line passing through the point(-2,1) will have to have slope = -2/3. We know that the line is sloping down to the right because the slope is negative. The slope is also the change in y divided by the change in x, so for each change of 3 on the x-axis, the y value decreases by 2 (that is, -2/3). To define a line, we need another point to pair with (-2,1). We know that the general equation for a line is . We know one y and one x, but we don't know b, so we substitute what we know and solve that. so Recall the b is called the y-intercept, which tells us where the line crosses the y-axis when x=0. That gives us another coordinate pair: (0, -1/3). So the equation for the line is: .
 Mixture_Word_Problems/100214: You need to measure one cup of water. You have been given a container that holds 5 cups of water, a container that holds 3 cups of water, and a large bucket of water. How can you measure exactly one cup by using these supplies? You may switch the water from one container to another, but may not mark water levels in any way.1 solutions Answer 72982 by oberobic(2304)   on 2007-09-24 23:25:55 (Show Source): You can put this solution on YOUR website!Fill the 3c container. Pour it into the 5c container. Refill the 3c container. Pour into the 5c container until the 5c container is full. You will have 1c left in the 3c container.
 Radicals/100105: Solve each the equations. check the solutions sqrt 4+1+3=01 solutions Answer 72977 by oberobic(2304)   on 2007-09-24 22:47:37 (Show Source): You can put this solution on YOUR website!You've left something out. sqrt of 4 = 2, and 2+1+3 cannot equal 0. sqrt or (4+1+3) = sqrt of 8 = 2 * sqrt 2, which is not equal 0.
 Quadratic_Equations/100153: Geomatry. The length of a rectangle is 1 cm longer than its width. If the diagnonal of the rectangle is 4cm what are the dimensions (the length and teh width) of the rectangle?1 solutions Answer 72975 by oberobic(2304)   on 2007-09-24 22:41:09 (Show Source): You can put this solution on YOUR website!The statement that the "length is 1 cm longer than the width" means that we can define the length (l) = w + 1. Width (w) is simply = to w. So, the rectangle has sides of w, w+1, w, and w+1. The diagonal is known to be 4 cm (given). Now we simply apply the Pythagorean formula. Let's call the diagonal d. That means Therefore, Of course, is the square of the diagonal, and we were told the diagonal was 4 cm, so . Substituting what we know: Subtracting 16 from both sides: This does not factor easily, so you can use the quadratic equation to find w. Quadratic formula: Substituing, we have
 Expressions-with-variables/100202: This question is from textbook Algebra structure and Method Please help me confirm I am doing this correctly: 4(2(-5x+y)-y)-10(y-4X) with the outside set of parenthesis being brackets1 solutions Answer 72970 by oberobic(2304)   on 2007-09-24 22:07:37 (Show Source): You can put this solution on YOUR website!Using brackets helps visually, but nested parentheses are okay, too. 4[2(-5x+y)-y]-10(y-4x) means 4 * (2 * (-5x + y) - y) - 10*(y - 4x). Then you simplify the innermost parentheses repeatedly. But you have to remember the rules of precedence: exponentiation, then multiplication and division (left to right), then addition and subtraction (left to right). 4 * (2 * (-5x + y) - y) - 10*(y - 4x) becomes 4 * (-10x + 2y - y) - 10*(y - 4x) because you do the multiplication before subtracting the y. Solving inside the parentheses is next: 4 * (-10x + y) - 10*(y - 4x) Now multiply left to right: -40x + 4y - 10y + 40x because mutiplying -4x by -10 is +40x. The -40x cancels + 40x, so we end up with -6y
 Finance/100170: what is the volume if the width of a rectangular prisom is 42", the lengh being 6 feet, and the height being 3 feet?1 solutions Answer 72968 by oberobic(2304)   on 2007-09-24 21:58:48 (Show Source): You can put this solution on YOUR website!To compute volume you multiple length by width by depth (or height, as the case may be). BUT, all of the values must have the same units of measure. Here you have 42" for one dimension. The other two dimensions are in feet: 6 feet and 3 feet. So, you have to convert 42" to feet, or 6 feet and 3 feet to inches, before you multiply. Dividing 42" by 12" per foot, you get 3.5 feet. So the volume is simply 3.5 times 3 times 6 cubic feet.
 Expressions-with-variables/100197: This question is from textbook middle grades math Please help show me where i am going wrong; On the two days before a swim meet, jesse swan a total of 2050 meters. The second day she swam 250 meeters more than the first day. How many meters did she swim on each day? m+250=2050 m=1800 1800-250=500 500+250=750 1st day 2050-750=1600 2nd day I know this to be wrong, book says 900 and 11501 solutions Answer 72967 by oberobic(2304)   on 2007-09-24 21:51:27 (Show Source): You can put this solution on YOUR website!On the first day Jesse swam fewer meters than the second day, so let's call that x. The total is 2050, so on the second day Jesse swam 2050-x meters. We also know that on the second day Jesse swam 250 meters more than the first day. Recall that the first day was x and that the second day is 2050-x. So to make them equal, you have to add 250 meters to the first day, so it becomes x+250. x + 250 = 2050 - x Adding an x to both sides of the equation, we obtain: 2x + 250 = 2050 Subtracting 250 from both sides, we obtain: 2x = 1800 Dividing both sides of the equation by 2: x = 900 So, Jesse swam 900 meters on the first day. Adding 250 we get 1150, which is the number of meters swam on the second day. Checking these answers, we find that 900 + 1150 = 2050, which is the correct total.