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# Recent problems solved by 'Mathtut'

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 Matrices-and-determiminant/176529: How do I multiply: 2EA E=[1, 2] a=[3, 0, 2, -1]1 solutions Answer 131627 by Mathtut(3670)   on 2009-01-13 21:52:26 (Show Source): You can put this solution on YOUR website!2EA: I am going to assume the A is a 2x2 matrix because in order for E which is a 1x2 matrix, to be multiplied by another matrix, the other matrix rows must be 2 : 2==
 Inequalities/176541: A metal stays solid at Fahrenheit temperatures below 1760.2 degrees. Determine (in terms of an inequality) those Celsius temperatures for which metal stays solid. Use the formula F=9/2C+32. The solution set is {C|C<1 solutions Answer 131623 by Mathtut(3670)   on 2009-01-13 21:39:28 (Show Source): You can put this solution on YOUR website!so lets just plug in our known and solve for C. than 9/2 you typed should be 9/5 : 1760.2=9/5(C+32) : 8801=9C+288 : 9C=8513 : degrees Celcius : degrees
 Travel_Word_Problems/176536: It take Felicia 25 minutes to walk one mile. At this rate, how long would it take her to walk 7 miles? I multiplied 25 x 7 = 175 minutes. But am confused trying to use the formula. D=RT D=7 miles, R=25 min/mile, T=T 7=25T 7/25 = T T= .28 minutes What am I not understanding? Thanks for your help!1 solutions Answer 131621 by Mathtut(3670)   on 2009-01-13 21:35:19 (Show Source): You can put this solution on YOUR website!you must pay attention to your units and make sure you interpret what the rate is as opposed to the distance and time. : the rate is not 25 minutes..... the rate is 1mi/25min : so 7mi=(1/25)(mi/min)(t) : t=7mi(25/1 (min/mi))...see how the units cancel each other so that we end up with 175 min. : the way you were doing it you ended up with
 Inequalities/176537: You are taking a Spanish course in which there will be four tests, each worth 100 points. You have scores of 98.91, and 92 on the first three tests. You must make a total of 360 in order to get an A. What scores on the last test will give you an A?1 solutions Answer 131617 by Mathtut(3670)   on 2009-01-13 21:21:57 (Show Source): You can put this solution on YOUR website!91+92+98+x=360 : 281+x=360 : must be scored to avg 90 per test or to have a total of 360 points
 Pythagorean-theorem/176467: Everybody knows that the Pythagorean Theorem works, and I can probably find a mathematical proof that is satisfying, but I want to know why, in ordinary, conversational terms, why it works! Thanks so much!1 solutions Answer 131609 by Mathtut(3670)   on 2009-01-13 20:41:28 (Show Source): You can put this solution on YOUR website!this reading might interest you : this one is an animation: : http://www.davis-inc.com/pythagor/index.shtml : http://jwilson.coe.uga.edu/EMT668/emt668.student.folders/HeadAngela/essay1/Pythagorean.html
 Age_Word_Problems/176508: Two-thirds of someone's age three years ago plus one sixth of someone's age three years from now will equal someone's age four years ago. How old is someone now?1 solutions Answer 131607 by Mathtut(3670)   on 2009-01-13 20:30:39 (Show Source): You can put this solution on YOUR website!someone's age ....lets call s : 2/3(s-3)+1/6(s+3)=s-4 : (2/3)s-2+(1/6)s+(1/2)=s-4 : 4s-12+s+3=6s-24 : :
 Age_Word_Problems/176507: One-half of someone's age four years from now minus three-fourths of someone's age four years ago is zero. What is someone's present age?1 solutions Answer 131606 by Mathtut(3670)   on 2009-01-13 20:21:04 (Show Source): You can put this solution on YOUR website!lets call someone's age x : 1/2(x+4)-3/4(x-4)=0....equation : (1/2)x+2-(3/4)x+3=0...distributed terms : 2x+8-3x+12=0...multiplied all terms by 4 : -x=-20 : years old
 Linear-systems/176481: How do I write an equation for a line whose slope is undefined and passes through (6, 4)?1 solutions Answer 131604 by Mathtut(3670)   on 2009-01-13 20:09:17 (Show Source): You can put this solution on YOUR website!if the slope is undefined then we know the equation takes the form of x=a, where a is the value of the x coordinate of any point on the line. : hence x=6 is our equation
 Complex_Numbers/176496: how do I simplifiy the fraction -(2x over -xy)?1 solutions Answer 131602 by Mathtut(3670)   on 2009-01-13 20:05:52 (Show Source): You can put this solution on YOUR website! -(2x over -xy) : :
 Equations/176484: This question is from textbook 1 solutions Answer 131600 by Mathtut(3670)   on 2009-01-13 20:01:12 (Show Source): You can put this solution on YOUR website!need a question........thanks Mathtut
 Linear-equations/176485: Create an equation of a nonlinear function and provide two more examples 1 solutions Answer 131599 by Mathtut(3670)   on 2009-01-13 20:00:38 (Show Source): You can put this solution on YOUR website! : :
 Linear_Algebra/176486: what is 18r^4s^5t^6 divided by -3r^2st^3?1 solutions Answer 131597 by Mathtut(3670)   on 2009-01-13 19:53:25 (Show Source): You can put this solution on YOUR website! : :
 Linear_Equations_And_Systems_Word_Problems/176487: During a sale an automobile dealer sold 69 cars and trucks. If she sold 27 more cars than trucks how many trucks did she sell?1 solutions Answer 131595 by Mathtut(3670)   on 2009-01-13 19:47:48 (Show Source): You can put this solution on YOUR website!let x and y be the number of cars and trucks sold respectively : x+y=69........eq 1 x=y+27........eq 2 : take x's value from eq 2 and plug it into eq 1 : y+27+y=69 : 2y=42 : number of trucks sold : number of cars sold
 Equations/176488: 8-P=-12-3P1 solutions Answer 131594 by Mathtut(3670)   on 2009-01-13 19:44:31 (Show Source): You can put this solution on YOUR website!8-P=-12-3P : 2P=-20......added 3P and subtracted 8 from both sides : divided both sides by 2 to isolate the variable P
 Geometry_Word_Problems/176480: "A certain angle is 30 degrees less than 4 times it's compliment. Find the angle's supplement." I need a step by step answer to the above word problem. Thank you in advance.1 solutions Answer 131593 by Mathtut(3670)   on 2009-01-13 19:41:31 (Show Source): You can put this solution on YOUR website!let a and b be our supplementary angles : b=4a-30..........eq 1 a+b=180..........eq 2 : rewrite eq 2 to b=180-a and plug it into eq 1 : 180-a=4a-30 : 5a=210 : degrees : degrees
 Inverses/176475: If two numbers are opposite of each other, are their reciprocals also opposite of each other? 1 solutions Answer 131588 by Mathtut(3670)   on 2009-01-13 19:31:33 (Show Source): You can put this solution on YOUR website!3 and -3---->1/3 and -1/3 : in general if -a is the opposite of a is -1/a the opposite of 1/a : if -a+a=0 : then is(-1/a)+(1/a)= to zero -1+1/a=0/a=0 : it appears as if the answer is YES
 Probability-and-statistics/176476: arrange these # in order from least to greatest : 25%, 0.5, 3/5, 0.45, 4/20, 65% flip a coin and roll a die find P ( tails and mutiple of 3)1 solutions Answer 131586 by Mathtut(3670)   on 2009-01-13 19:23:00 (Show Source): You can put this solution on YOUR website!4/20,25%,.45,.5,3/5,65%
 Graphs/176465: This question is from textbook Virginia Algebra I graph each question. y-2=(x-3)1 solutions Answer 131583 by Mathtut(3670)   on 2009-01-13 19:06:12 (Show Source): You can put this solution on YOUR website!y=x-1 :
 Linear_Equations_And_Systems_Word_Problems/176462: can you help with this problem: ten gallons of a 30% acid mixture is obtained by mixing a 20% solution with a 50% solution. How much of each must be used? i've tried creating two linear equations (one for total volume and one for concentration) but i don't know where to go from there.1 solutions Answer 131581 by Mathtut(3670)   on 2009-01-13 19:05:15 (Show Source): You can put this solution on YOUR website!ok lets call the amount of 20% and 50% solutions a and b respectively : a+b=10...........eq 1 .2a+.5b=.3(10)...eq 2 : rewrite eq 1 to a=10-b and plug this value into eq 2 : .2(10-b)+.5b=3 : 2-.2b+.5b=3 : .3b=1 : amount of 50% solution : amount of 20% solution
 Quadratic_Equations/176455: This is related to quadratic equations and complex numbers. The equation is x^2+mx+n=0 One of the roots/solutions is 3+2i. What is the value of m?1 solutions Answer 131579 by Mathtut(3670)   on 2009-01-13 18:57:17 (Show Source): You can put this solution on YOUR website!if one solution is 3+2i then the other is 3-2i : : : : : value of m=-6
 Number-Line/176457: 17h+h+16-6h1 solutions Answer 131576 by Mathtut(3670)   on 2009-01-13 18:52:49 (Show Source): You can put this solution on YOUR website!combine all like terms :
 Linear-systems/176458: How do I graph: 4y-3x=12?1 solutions Answer 131575 by Mathtut(3670)   on 2009-01-13 18:51:30 (Show Source): You can put this solution on YOUR website!4y=3x+12 : y=(3/4)x+3 : slope is 3/4, y intercept is 3 : make a table for any given value of x find y and then plot those point and you will end up with this line :
 Radicals/176454: This question is from textbook mathatics for the caribbean 3 1 solutions Answer 131570 by Mathtut(3670)   on 2009-01-13 18:35:34 (Show Source): You can put this solution on YOUR website!need a question ....thanks Mathtut
 Points-lines-and-rays/176451: This question is from textbook Give an equation of each line described. Use the form specified by your teacher. slope : 2 y-intercept: 51 solutions Answer 131567 by Mathtut(3670)   on 2009-01-13 18:22:24 (Show Source): You can put this solution on YOUR website!y=mx+b is slope intercept form just plug em in : y=2x+5
 Miscellaneous_Word_Problems/176450: This question is from textbook a truck is 26 feet long. Find the length on a scale model if 1 inch represents 5 1/2 feet. Round to the nearest tenth if necessary. 1 solutions Answer 131566 by Mathtut(3670)   on 2009-01-13 18:21:29 (Show Source): You can put this solution on YOUR website!so you would divide 26ft/5.5ft to find out how many intervals of 5.5 there are. : 26/5.5=4.7 : so we need 4.7 inches on the scale model to represent 26 ft : 5.5(4.7)=26
 Miscellaneous_Word_Problems/176420: Mr.McKay can save 2% of his fuel bill if he pays within 10 days. About how much would he save on a fuel bill of 119.75 ?1 solutions Answer 131536 by Mathtut(3670)   on 2009-01-13 16:29:38 (Show Source): You can put this solution on YOUR website!119.75(.02)=2.4 dollars
 Linear-systems/176424: please answer my question: write an equation of the line that passes through (-5,3) and is perpendicular to the x-axis in slope-intercept form 1 solutions Answer 131534 by Mathtut(3670)   on 2009-01-13 16:24:55 (Show Source): You can put this solution on YOUR website!y=0 is the x axis and we know the slope is zero so we have the slope and a point : the slope of a vertical line which would be perpendicular to the x axis is undefined . So the answer would be a vertical line with an equation of x=-5 which is parallel to the y axis and 5 units to the left of it.
 Polygons/176413: This question is from textbook I need help with #16,how to find the measure of a 20-gon angle. Here are the directions, " find the measure of an angle in each polygon if the polygon is regular. Round to the nearest tenth of a degree if necessary.1 solutions Answer 131516 by Mathtut(3670)   on 2009-01-13 15:23:39 (Show Source): You can put this solution on YOUR website!the formula for finding the sum of interior angles for a regular polygon is 180(n-2)....so since n=20 we arrive at : 180(18)=3240 degrees : now since there are 20 equal angles we divide this by 20 to get the measurement of 1 : 3240/20=162 degrees each
 Functions/176408: What similarities and differences do you see between functions and linear equations Are all linear equations functions? Is there an instance in which a linear equation is not a function? Support your answer. Create an equation of a nonlinear function and provide two inputs for your classmates to evaluate. 1 solutions Answer 131513 by Mathtut(3670)   on 2009-01-13 15:00:55 (Show Source): You can put this solution on YOUR website!functions map inputs to unique outputs. A polynomial function of the first degree, such as y = 2x + 1, is called a linear function All linear equations are functions with the exception of one type-- : Use the vertical line rule to see if an equation is a function or not. If a vertical line intersects a plot at more than one point, the equation is NOT a function. : So, there is a linear equation that is not a function. Using the vertical line rule we conclude that a vertical itself is not a function. Maybe it would be easier to look at this from another definition of function. There is one and only one y value for each value of x. For x=a, there is infinite values of y. Thus a vertical line is not a function. nonlinear function f(x) = x^2-1
 Divisibility_and_Prime_Numbers/176345: which is the greatest 3 digit number exactly divisible by 8,10,121 solutions Answer 131509 by Mathtut(3670)   on 2009-01-13 14:46:14 (Show Source): You can put this solution on YOUR website!960....which is 8 times 10 times 12. lets test numbers of above that : since it has to be divisible by 12 lets add 12 to 960 : 960+12=972...10 doesnt work here : 972+12=984...10 doesnt work here : 984+12=996...10 doesnt work here : any other additions of 12 would take us to 4 digits.
 Quadratic_Equations/176362: Write a quadratic equation in the variable x having the given numbers as solutions. Type the equation in standard form, ax^2+bx+c=0 Solution: 3 (only solution) Any help would be much appreciated Thank you 1 solutions Answer 131507 by Mathtut(3670)   on 2009-01-13 14:35:55 (Show Source): You can put this solution on YOUR website! since 3 is the only solution :