Questions on Algebra: Systems of Linear Equations answered by real tutors!

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Question 277798: A cellular phone company offers a contract for which the cost C in dollars,of t minutes if telephoning is given by C=0.25(t-300)+59.95, where it is assumed that t>300 minutes. What times will keep costs between $107.70 and $125.70?
Click here to see answer by checkley77(12569)

Question 277857: {6x+4y=12
{2y=6-3x
graph and classify each system. Then find the solution from the graph
Click here to see answer by richwmiller(9143)

Question 277864: the sum of the length of any two sides of a triangle must be greater than the third side. if a triangle has one side that is 7 inches and a second side is 2 inches less then twice the third side. what are the possible lenghts for the second and third sides?
Click here to see answer by edjones(7569)

Question 277922: I am not sure how to work these three problems :
For the systems of linear equations in questions 1-3
Determine how many solutions exist
Use either elimination or substitution to find the solutions (if any)
Graph the two lines, labeling the x-intercepts, y-intercepts, and points of intersection
1.y = 2x + 3 and y = -x - 4
2.2x + 3y = 8 and 3x + 2y = 7
3.2x + 3y = 8 and 3x + 2y = 7

Click here to see answer by nabla(475)

Question 277788: Snookers Lumber can convert logs into either lumber or plywood. In a given day,the mill turns out three times as many units of plywood as lumber. It makes a profit of $30 on a Unit of lumber and $45 on a unit of plywood. How manyof each unit must be produced and sold in order to make a profit of 16665.?
Click here to see answer by ankor@dixie-net.com(15652)

Question 278155: hello
how would i solve this linear system using the cramers rule?
4x-7y-7z= -26
3x-7y-9z=-26
-9x-5y-2z= -51
this is what i have done but it seems wrong
i get that d = -145
dx = -1939/ -145
dy = 1175/-145
dz = -1428/-145
this answers seem to work only with the first equation.

Click here to see answer by jim_thompson5910(28595)

Question 278183: 4.00x + 6.00y = 2340
x + y = 480

Click here to see answer by stanbon(57354)

Question 278248: 4x-2y=4
-20x+10y=-20
is there no solution and does the graph only intersect at 1 point so the solution is unique?
Click here to see answer by jim_thompson5910(28595)

Question 278160: How do you solve this three variable equation?
d + e - f = 11
f + d + 5 = e
2e - 12 = f
Click here to see answer by ankor@dixie-net.com(15652)

Question 278302: The degree measure of one of two supplementary angles is 6 more than one half that of the other. What are the degree measures of the angles?
Click here to see answer by Grinnell(63)

Question 278341: i am currently doing a section on this in my class called sloving linear equations by graphing and i dont understand how u do it can u help me?
Click here to see answer by Theo(3464)

Question 278319: SOLVE BY ELIMINATION METHOD
3X+2Y=-3
8X-2Y=-52
Click here to see answer by JBarnum(2044)

Question 278338: x-y=5
x-y=3
Click here to see answer by JBarnum(2044)

Question 278409: directions state:
graph each linear equation in two variables & find three solutions in your table of values for equation.
y=-1/2x
Click here to see answer by JBarnum(2044)

Question 278510: Solve for X and Y, two system equation:
Equation1 4X+Y=17 Equation2 2X+3Y=21
Click here to see answer by checkley77(12569)

Question 278562: Find the point-slope form of the equation of the line satisfying the given conditions and use this to write the slope-intercept form of the equation.
x-intercept = 3 and y-intercept = 2

Click here to see answer by nyc_function(2733)

Question 278588: how many liters of pure hydrochloric acid must be added to 60 liters of a solution that is 10% hydrochloric acid to get a solution that is 15% hydrochloric acid?
Click here to see answer by nyc_function(2733)

Question 278965: Solve using the elimination method. Show your work. If the system has no solution or an infinite number of solutions, state this.
1/5x - 1/4y = 3
2/5x + 1/2y = 2
I tried this problem on my own and was thinking that I would have to multiply the equations for example:
1/5x - 1/4y * 2/5x = 3 * 2/5x
Click here to see answer by Edwin McCravy(8909)

Question 278978: When you solve a system of linear equations, and you get your x or y how do I know which of the two equations to plug my answer into ?
Click here to see answer by Edwin McCravy(8909)

Question 279086: Solve each system.
Number One:
y = 2x + 8
y = 3x - 1

Number Two:
2x - y = 2
2x - 2y = 4

Number Three:
-x + y = 2
2x + y = -1
Click here to see answer by stanbon(57354)

Question 279132: Please help solve these 3 system equations for X and Y and Z
Equation1. X+Y+2Z=5
Equation2. X+Y=5
Equation3. X+3Y+Z=11
Equation1. 2X+2Y+4Z=10
Equation2. 3X+3Y=15
Equation3. 4X+12Y+4Z=44
What is the difference between these systems of equations?
Click here to see answer by J2R2R(94)

Question 279066: please help me with the following linear equation with decimals:
x-0.08x=460
and 2x/2 = x
Click here to see answer by mananth(12270)

Question 279354: jack and betty have 28 coins that are nickels and dimes if the value of the coins is $1.95 how many coins of each type do they have

Click here to see answer by josmiceli(9680)

Question 279354: jack and betty have 28 coins that are nickels and dimes if the value of the coins is $1.95 how many coins of each type do they have

Click here to see answer by JBarnum(2044)

Question 279393: What is the slope of the line 4x+2y=10?

Click here to see answer by richwmiller(9143)

Question 279605: My homework is to graph systems of inequalities. The problem I'm having trouble with is:
x-3y>(or equal to)-7
5x+y<(or equal to)13
x+6y>(or equal to)-9
3x-2y>(or equal to)-7
I have successfully graphed the first two, but I cannot figure out the third or last one yet. I graphed what I thought the third one looked like, but it didn't make any sense to the problem. I set the y-intercept at -1 1/3 with a slope of -9/6 which reduces to -3/2.
Click here to see answer by Theo(3464)

Question 279699: How do you solve systems by graphing... for example (2x+2y=5 & y=x-4)What would the steps be to solving this (or any) problem.
Click here to see answer by Alan3354(30993)

Question 279819: how do u solve the following problem:
y=3x
x+y=4
Click here to see answer by JBarnum(2044)

Question 279894: Number One:
5x + 4y - z = 1
2x - 2y + z = 1
-x - y + z = 2

Number Two:
x + y + z = 0
2x + 3y +2z = -1
x - y + z = 2

Number Three:
x + 2y = 0
4x - z = 4
5y + z = -1
Click here to see answer by Edwin McCravy(8909)

Question 279134: Please solve these three system equation for X and Y and Z.
Equation1. X+10Y+Z=52
Equation2. 5X+Y+4Z=15
Equation3. X+2Y-3Z=12
Click here to see answer by JBarnum(2044)

Question 280013: How do I solve the system using the substitution method and show work?
2x+3y=2
x+3y=10
Click here to see answer by nabla(475)

Question 280013: How do I solve the system using the substitution method and show work?
2x+3y=2
x+3y=10
Click here to see answer by jsmallt9(3296)

Question 280016: THE DISTANCE BETWEEN THE PLANE x + 2y - 2z = 3 and 2x + 4y - 4z = 7
Click here to see answer by nabla(475)

Question 276320: how do i do -2x+4y=0
-8x+y=15
Click here to see answer by nabla(475)

Question 280099: train A is traveling at 60 mph and train B at 80 mph. train A passes the station at 810 and train B at 825 at what time will train B catch train A?
Click here to see answer by josmiceli(9680)

Question 280111: x+9y =2 (1)
x= 8-9y (2)
Click here to see answer by richwmiller(9143)

Question 280129: Solve this system: y=5x-1 and y=8x+4
Click here to see answer by richwmiller(9143)

Question 280114: in 1992 life expectancy was 63.4. in 1998 it was 67.0
E= life expectanc in year t and let t = # of years since 1992
what is the linear function for this?
what would the life expectancy be if E(16)
Click here to see answer by richwmiller(9143)

Question 280032: solve the linear system
-7x-8y=9
-4x+9y=-22

Click here to see answer by checkley77(12569)

Question 280178: 6x+2y=16
-2x+y=-2
Click here to see answer by richwmiller(9143)

Question 280178: 6x+2y=16
-2x+y=-2
Click here to see answer by JBarnum(2044)

Question 280166: Metro Concerts can rent a truck for either $55 with unlimited mileage or $29 plus 40 cents per mile. For what mileages would the unlimited mileage plan save money?
Write an inequality to describe the situation.
Solve the inequality.

Click here to see answer by richwmiller(9143)

Question 280140: slove the follwing system of equation using subatitution 3x+6y=48 and-5x+6y=32
Click here to see answer by checkley77(12569)

Question 280247: 4y-2=33-3y
Click here to see answer by rfer(12660)

Question 280413: I need help in solving this equation - I came up with x=7 and got it wrong.
3[x-2] +2=17
Thanks
Click here to see answer by dabanfield(803)

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