# Questions on Algebra: Matrices, determinant, Cramer rule answered by real tutors!

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 Question 448128: The charge for electricity is 3 cents per unit for lighting and 1/2 cents per unit for heating.A man's bill for a quarter should have been \$8. by mistakes his lighting was charged at 1/2cents per unit and his heating at 3 cents per unit. the amount of the bi1l was \$13. use any matrix method to find how many units of electricity he used altogether Click here to see answer by stanbon(60771)

 Question 449181: Can someone please show me step by step how to solve this problem using matrices? I’m missing something somewhere, Thanx. x – y + 4z = 6 2x + z = 1 x +5y + z = -9 Click here to see answer by ewatrrr(11139)
 Question 449181: Can someone please show me step by step how to solve this problem using matrices? I’m missing something somewhere, Thanx. x – y + 4z = 6 2x + z = 1 x +5y + z = -9 Click here to see answer by stanbon(60771)

 Question 451556: Find the value of the following: 6!11! _______ 4!9! Click here to see answer by pedjajov(51)

 Question 452469: Please help me this equation step by step: [-5 -1 9 |-2] [1 2 6 |-17] [5 -8 -2 |-3] I don't understand how to get it as 1 0 0 ratio... 0 1 0 0 0 1 Click here to see answer by stanbon(60771)

 Question 454542: I just want this answer explained to me. The question ask me to use the rref function in my calculator and the answer I received was as follows. 1 0 -.33 0 0 1 -2.33 0 0 0 0 1 How do I know if this equation has any solutions or no solutions and simply could you tell me if I did the problem correct. The problem goes as follows 2x+y-3=1 x-y+2z=1 5x-2y+3z=6 Click here to see answer by solver91311(18785)

 Question 455380: I need help solvings this problem the question says to find the determant by using expansion by minor numbers | -3 5 1 | | 5 -3 2 | } 2 2 2 | Click here to see answer by Alan3354(34673)

 Question 456150: find ab if, A=7 3 1 4 2 5 b=6 -3 0 -4 2 -1 Click here to see answer by robertb(4012)

 Question 461402: Help! What is the solution to the system below? 3x + y + z = 18 4x + 2y + 3z = 12 7x + 8y + 5z = 9 Click here to see answer by rwm(914)

 Question 463661: I need help with the following: Write an augmented matrix for the system of equations 9x+3y=75 3y=3 A)[9 3|75] [0 3|3 ] b) [3 0|3] [9 3|3] c) [75 3|9] [ 3 o|3] D) [9 3|75] [3 3| 0] I'm thinking it's A but I'm not 100% positive. Thanks for your help. Click here to see answer by MathLover1(7480)

 Question 463663: if matrix a=matrix b what are the values of x,y,z? a 2 5y 3 12z b 10x 15 3 48 Click here to see answer by math-vortex(472)

 Question 464224: I'm having trouble answering this question my calculators aren't answering it right because I can't format it correctly for some reason. The reduced row echelon form of the augmented matrix of a system of equations is given. Find the solutions of the system. [1 0 0 0 |3/2] [0 1 0 0 | 17] [0 0 1 0 | -5] [0 0 0 1 | 0 ] Click here to see answer by Alan3354(34673)

 Question 464642: Solve using Cramer's Rule. x + 3y + 5z = 6 2x - 4y + 6z = 14 9x - 6y + 3z = 3 I came up with (1,-2,1) but Cramers rule confuses me so I don't know if I did it right Click here to see answer by MathLover1(7480)
 Question 464642: Solve using Cramer's Rule. x + 3y + 5z = 6 2x - 4y + 6z = 14 9x - 6y + 3z = 3 I came up with (1,-2,1) but Cramers rule confuses me so I don't know if I did it right Click here to see answer by Alan3354(34673)
 Question 464642: Solve using Cramer's Rule. x + 3y + 5z = 6 2x - 4y + 6z = 14 9x - 6y + 3z = 3 I came up with (1,-2,1) but Cramers rule confuses me so I don't know if I did it right Click here to see answer by Edwin McCravy(9716)

 Question 464639: Solve the system using Cramer's rule. 4x + y = -11 3x - 5y = -60 I came up with the answer -5,9 but i'm not sure it's right Click here to see answer by ewatrrr(11139)
 Question 464639: Solve the system using Cramer's rule. 4x + y = -11 3x - 5y = -60 I came up with the answer -5,9 but i'm not sure it's right Click here to see answer by Alan3354(34673)

 Question 464638: How to write the determinants D, Dx, and Dy for the system given. but Do not solve. {2x + 5y = 7 {-3x + 4y = 1 Click here to see answer by Alan3354(34673)

 Question 463770: solve the augmented matrix for a three-equation system in three unknowns x, y, z. 3 1 -2: 10 0 2 -3: 4 0 0 1: 4 Click here to see answer by robertb(4012)

 Question 464916: Application, I am having a hard time setting this problem up. The snack shop makes three mixes of nuts in the following proportions: Mix I: 7 pounds peanuts, 5 pounds cashews, and 1 pound pecans. Mix II: 3 pounds peanuts, 2 pounds cashews and 2 pounds pecans. Mix III: 4 pounds peanuts, 3 pounds cashews, and 3 punds pecans. The shop has 67 pounds of peanuts, 48 pounds of cashews and 32 pounds of pecans in stock. How many of each mix can it produce? Click here to see answer by ewatrrr(11139)

 Question 465270: find the inverse of the matrix [-9 5, 6 -3] Click here to see answer by richard1234(5390)

 Question 465640: Determine the value of k for which the system has no solutions x+y+3z=-1 x+2y-2z=-2 4x+12y+kz=-11 Click here to see answer by ewatrrr(11139)

 Question 465679: The vectors v=(3,5,1),u=(-4,-8,-4+k), and w=(-2,-6,2) are linearly independent if and only if k= Click here to see answer by robertb(4012)

 Question 465677: let v1=(-3,2,4), v2=(-3,5,0), and y=(-18,24,h) for what value of h is y in the plane spanned by v1 and v2? Click here to see answer by robertb(4012)

 Question 467052: Please help me solve plese show step by step I think the answer is x= 19ft 9 in John increased the area of his garden by 120 ft2. The original garden was 12 ft. by 16 ft., and he increased the length and the width by the same amount. Find the exact dimensions of the new garden and approximate the dimensions in feet and inches. Discuss which method you used to solve the problem and why you chose this method. Click here to see answer by Alan3354(34673)
 Question 467052: Please help me solve plese show step by step I think the answer is x= 19ft 9 in John increased the area of his garden by 120 ft2. The original garden was 12 ft. by 16 ft., and he increased the length and the width by the same amount. Find the exact dimensions of the new garden and approximate the dimensions in feet and inches. Discuss which method you used to solve the problem and why you chose this method. Click here to see answer by Theo(3552)

 Question 469166: 2 3 4 15 12 3 4 5 28 20 4 5 6 X 30 5 6 7 66 42 6 7 8 91 56 Find X Click here to see answer by Tatiana_Stebko(1410)

 Question 470317: Hi. I need some assistance on how to work this problem out. Consider this system: {3(x+y)=x-3 -y=2x+3/3 I need to figure out if they are dependent or independent and if it's consistent or inconsistent. Thank you for your time. Click here to see answer by ewatrrr(11139)

 Question 471062: How do I solve the following system of equation using matrices? x-3y+z= -21 2x-y+z=-9 2x+y+5z=-31 Thanks in advance! Click here to see answer by ccs2011(207)