Maths

posted by .

Can you pliz help me solve the following simultaneous equation 3x-y=2 and 3y+9x=4

  • Maths -

    3x-y=2 Multiplt it by 3
    9x-3y=6 Add to it the other eq.
    9x+3y=4 You get 18x=10 or x=5/9
    Substitute in any eq.
    3*5/9-y=2 or y=15/9-2=5/3 -2
    or y=(5-6)/2=-1/6.
    Check: 3*5/9-(-1/6)=2 or 5/3+1/6=2
    or (10+2)/6=2 ok.
    9*5/9-3*1/3=4 or 5-1=4 ok.

  • check answer - Maths -

    or ... using substitution

    from the 1st: y = 3x-2
    sub into the 2nd

    3(3x-2) + 9x = 4
    9x - 6 + 9x = 4
    18x = 10
    x = 5/9

    back into the 1st:
    y = 3(5/9) - 2
    = 5/3 - 2
    = -1/3

    in original:
    1st equation:
    LS = 3(5/9) - (-1/3) = 6/3 = 2 = RS
    2nd equation:
    LS= 3(-1/3) + 9(5/9) = -1 + 5 = 4 = RS

    So x = 5/9 and y = -1/3

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Maths

    solve the following pair of simultaneous equation: (x/a)+(y/b)=1 (x/b)+(y/a)=1 can someone help please?
  2. maths pls help

    1. Solve the following simultaneous equations: log2 xy = 7 log2 (x^2/y) = 5 2. If log y x =a and log z x=b where x is not equal to 1, express the following in terms of a and b: logy (yz) Solve the following simultaneous equations: …
  3. maths

    solve the following simultaneous equation: 5x+2y=29 x-y=-4 2x-y=-1 3x-y=2 5x+y=16 x-2y=1 5x+2y=16 -3x+4y=-7 3x+2y=19 5x-2y=5 7x-1/3-2(7y+3)/5=10/3 5x+2/4+3y-2/5=16/5
  4. maths

    Solve the following simultaneous equation: 8x+3y=23 6x+5y=9
  5. maths

    solve the following simultaneous linear equation: -5x+6y=44 9x+7y=-8
  6. maths

    helo sir/madam can u help me to solve this problem solve the following simultaneous equation logx Y+logy X=5/2 xy=64
  7. Maths

    Solve the following simultaneous equation by substitution method 5x+y=35 & 3x-2y=14
  8. Maths:simultaneous equation

    Plz help me solve for x and y x^3+y^3=1 x^4+y^4=1 help?
  9. maths

    solve the simultaneous equation 1/y + 1/x =5 .......(i ) 1/x - 1/y =1 ........(i i )
  10. Maths

    To solve the simultaneous equation 1.4x + 3y = -1 2y - 3x = -12

More Similar Questions