Rearrange the following equation to make x the subject, and select the correct rearrangement from th

Discussion in 'Calculator Requests' started by math_celebrity, Jan 8, 2017.

  1. math_celebrity

    math_celebrity Administrator Staff Member

    Rearrange the following equation to make x the subject, and select the correct rearrangement from the list below
    3x + 2y 1
    -------- = ---
    4x + y 3

    • x = 7y/13
    • x = 7y/5
    • x = -7y
    • x = -3y
    • x = 3y/5
    • x = -5y/13
    • x = -y

    Cross multiply:
    3(3x - 2y) = 4x + y

    Multiply the left side through
    9x - 6y = 4x + y

    Subtract 4x from each side and add 6y to each side
    5x = 7y

    Divide each side by 5 to isolate x, the subject of an equation is the variable to the left
    x = 7y/5
     

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