Need Help With ONE Math Problem?

How many solutions are there to the following system of equations?

3x - 9y = 0

-x + 3y = -3

A. 0

B. 1

C. 2

D. Infinitely Many

3 Answers

Relevance
  • Anonymous
    9 years ago
    Favorite Answer

    Well first you've got to solve for X and Y by solving first for X in the first equation then putting it in for X in the second equation.

    3x - 9y = 0

    3x = 9y

    x = 3y

    -x + 3y = -3

    -(3y) + 3y = 3

    -3y + 3y = 0

    0y=0

    And that looks like it sucks so let's start the other way with Y.

    -x + 3y = -3

    3y = -3 + x

    y = -1 + 1/3x

    3x - 9y = 0

    3x - 9 (-1 + 1/3x) = 0

    3x + 9 -3x = 0

    9 = 0

    And that doesn't make sense either.

    I choose A.

    Source(s): math genius
  • 9 years ago

    3x-9y=0_-x+3y=-3

    Since 3y does not contain the variable to solve for, move it to the right-hand side of the equation by subtracting 3y from both sides.

    3x-9y=0_-x=-3y-3

    Multiply each term in the equation by -1.

    3x-9y=0_-x*-1=-3y*-1-3*-1

    Multiply -x by -1 to get x.

    3x-9y=0_x=-3y*-1-3*-1

    Simplify the right-hand side of the equation by multiplying out all the terms.

    3x-9y=0_x=3y+3

    Replace all occurrences of x with the solution found by solving the last equation for x. In this case, the value substituted is 3y+3.

    3(3y+3)-9y=0_x=3y+3

    Multiply 3 by each term inside the parentheses.

    9y+9-9y=0_x=3y+3

    Since 9y and -9y are like terms, add -9y to 9y to get 0.

    0+9=0_x=3y+3

    Remove the 0 from the polynomial; adding or subtracting 0 does not change the value of the expression.

    9=0_x=3y+3

    Since 9$0, there are no solutions.

    No Solution

    Answer is "A"

  • Anonymous
    9 years ago

    Keep the first equation as it is, but multiply the second equation by -3 and we get two equations

    3x - 9y = 0

    3x - 9y = 9

    Since the left sides are identical but the right sides are not, there are no possible solutions to these simultaneous equations.

Still have questions? Get your answers by asking now.