• How to solve x^3 + 4x = 0 ?

    9 answers · 2 weeks ago
  • 20/3 as a mixed number?

    14 answers · 2 weeks ago
  • Is it possible to solve for 3 unknown variables that are in 3 equations?

    Best answer: (1) : 3x + 2y + 7z = 100 (2) : 21x + 3y - 5z = 50 (3) : 4x - 2y + 3z = 20 You calculate [4 * (1)] - [3 * (3)] and you obtain the equation (4) (4) : 4.(3x + 2y + 7z) - 3.(4x - 2y + 3z) = (4 * 100) - (3 * 20) (4) : 12x + 8y + 28z - 12x + 6y - 9z = 400 - 60 (4) : 14y + 19z = 340 (4) : 14y = 340 - 19z (4) : y... show more
    Best answer: (1) : 3x + 2y + 7z = 100

    (2) : 21x + 3y - 5z = 50

    (3) : 4x - 2y + 3z = 20


    You calculate [4 * (1)] - [3 * (3)] and you obtain the equation (4)

    (4) : 4.(3x + 2y + 7z) - 3.(4x - 2y + 3z) = (4 * 100) - (3 * 20)

    (4) : 12x + 8y + 28z - 12x + 6y - 9z = 400 - 60

    (4) : 14y + 19z = 340

    (4) : 14y = 340 - 19z

    (4) : y = (340 - 19z)/14


    You calculate [1 * (7)] - (2)

    7.(3x + 2y + 7z) - (21x + 3y - 5z) = (100 * 7) - 50

    21x + 14y + 49z - 21x - 3y + 5z = 700 - 50

    11y + 54z = 650 → recall (4): y = (340 - 19z)/14

    11.[(340 - 19z)/14] + 54z = 650 → you multiply by 14 both sides

    11.(340 - 19z) + 756z = 9100

    3740 - 209z + 756z = 9100

    547z = 5360

    → z = 5360/547


    Recall (4): y = (340 - 19z)/14

    y = [340 - 19.(5360/547)]/14

    y = [340 - (101840/547)]/14

    y = (84140/547)/14

    → y = 6010/547


    Recall (1): 3x + 2y + 7z = 100

    3x + 2.(6010/547) + 7.(5360/547) = 100

    3x + (49540/547) = 100

    3x = 100 - (49540/547)

    3x = 5160/547

    → x = 1720/547
    13 answers · 3 weeks ago
  • 1-1/2+1/3-1/4+.....?

    Best answer: Let a(n) = (-1)^(n-1)*1/n and S(n) = [sum of i=1 to n] a(n) . a(1) = 1 , S(1) = 1 a(2) = -1/2 , S(2) = 0.5 a(3) = 1/3 , S(3) = 0.833... a(4) = -1/4 , S(4) = 0.58333... a(5) = 1/5 , S(5) = 0.78333... a(6) = -1/6 , S(6) = 0.61666... a(7) = 1/7 , S(7) = 0.75952... a(8) = -1/8 , S(8) = 0.63452... and so on . Let... show more
    Best answer: Let a(n) = (-1)^(n-1)*1/n and S(n) = [sum of i=1 to n] a(n) .
    a(1) = 1 , S(1) = 1
    a(2) = -1/2 , S(2) = 0.5
    a(3) = 1/3 , S(3) = 0.833...
    a(4) = -1/4 , S(4) = 0.58333...
    a(5) = 1/5 , S(5) = 0.78333...
    a(6) = -1/6 , S(6) = 0.61666...
    a(7) = 1/7 , S(7) = 0.75952...
    a(8) = -1/8 , S(8) = 0.63452...
    and so on .

    Let Osum(n) = S(2n-1) and Esum(n) = S(2n) .
    If n increases then Osum(n) always decreases and Esum(n) always increases .

    Osum(n) - Esum(n)
    = S(2n-1) - S(n)
    = S(2n-1) - [S(2n-1) + a(2n)]
    = -a(2n)
    = 1/(2n)
    It is positive so always Osum(n) > Esum(n) .
    And when n goes to +inf , Osum(n) - Esum(n) approaches 0 .

    So they have the common convergent value when n goes to +inf .
    Therefore , S(n) is convergent .

    (The convergent value is ln2 ≒ 0.69314 , but this proof can not find it .)
    8 answers · 3 weeks ago
  • How do you multiply monomials?

    How do you solve this? (3xyz)(2x^4 5y) It says to multiply monomials: 1) multiply their coefficients 2) Add their exponents When you multiply coefficients, do you multiply them all together, or only the ones with matching variables? For example do you multiply 3*2*5 or 3*2?
    How do you solve this? (3xyz)(2x^4 5y) It says to multiply monomials: 1) multiply their coefficients 2) Add their exponents When you multiply coefficients, do you multiply them all together, or only the ones with matching variables? For example do you multiply 3*2*5 or 3*2?
    11 answers · 2 weeks ago
  • Are there any mathematical entities that are non-transitive?

    I'm looking for something in mathematics in which A > B and B > C and C > A. An example of this is the rock-paper-scissors game. Are there any operations or elements in math that behave in a non-transitive wsy?
    I'm looking for something in mathematics in which A > B and B > C and C > A. An example of this is the rock-paper-scissors game. Are there any operations or elements in math that behave in a non-transitive wsy?
    8 answers · 2 weeks ago
  • Quick Algebra Question help?

    A truck can be rented from Company A for ​$70 a day plus ​$0.30 per mile. Company B charges ​$40 a day plus ​$0.50 per mile to rent the same truck. How many miles must be driven in a day to make the rental cost for Company A a better deal than Company​ B's?
    A truck can be rented from Company A for ​$70 a day plus ​$0.30 per mile. Company B charges ​$40 a day plus ​$0.50 per mile to rent the same truck. How many miles must be driven in a day to make the rental cost for Company A a better deal than Company​ B's?
    7 answers · 2 weeks ago
  • Need help on algebra....?

    Q1. 1/f=1/u+1/v solve for F and v Q2. V=R/R+r * i solve for r and R
    Q1. 1/f=1/u+1/v solve for F and v Q2. V=R/R+r * i solve for r and R
    7 answers · 2 weeks ago
  • 2.66 to a fraction?

    23 answers · 3 weeks ago
  • Vectors... How far will the boat travel when trying to cross this river ?

    Best answer: you are correct, if the river is 200 m wide, the boat will travel at least that distance. 80 m cannot be correct. for each second the boat travels, it moves 5 m across and the current pushes it down 2 m. The actual distance is √(5² + 2²) = √29 = 5.385 m. so it's speed is 5.385 m/s the direction is arctan 2/5... show more
    Best answer: you are correct, if the river is 200 m wide, the boat will travel at least that distance. 80 m cannot be correct.

    for each second the boat travels, it moves 5 m across and the current pushes it down 2 m. The actual distance is √(5² + 2²) = √29 = 5.385 m. so it's speed is 5.385 m/s

    the direction is arctan 2/5 = 21.8º

    which means the distance it travels is:
    cos 21.8º = 200/x
    x = 200/cos21.8 = 215 m

    my guess is that the 80 is BC
    tan 21.8 = BC/200
    BC = 80 m
    4 answers · 2 weeks ago
  • Formula for volume when given surface area....?

    The surface of a medallion is plated in gold. Given the surface area (SA) of a medallion and the thickness (t) of gold plated on the medallion, what is the formula to calculate the volume of gold plated on the medallion?
    The surface of a medallion is plated in gold. Given the surface area (SA) of a medallion and the thickness (t) of gold plated on the medallion, what is the formula to calculate the volume of gold plated on the medallion?
    5 answers · 2 weeks ago
  • Grade Help?

    Best answer: Assumption: Day 1 = 22/25 --> 88% Day 2 = 16/25 --> 64% Total = 38/50 --> 76% As you can see, if they are evenly weighted (same number of points each day), you can just average the two days. (88% + 64%) / 2 = 152% / 2 = 76% P.S. That's considered a C on standard grading scales, but your... show more
    Best answer: Assumption:
    Day 1 = 22/25 --> 88%
    Day 2 = 16/25 --> 64%

    Total = 38/50 --> 76%

    As you can see, if they are evenly weighted (same number of points each day), you can just average the two days.
    (88% + 64%) / 2
    = 152% / 2
    = 76%

    P.S. That's considered a C on standard grading scales, but your school/teacher may use a different scale.
    8 answers · 3 weeks ago