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    How would I solve this?

    4x + y = 25
    x - 3y = 16

    None of the coefficients are the same so I dont know what to do?
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    (Original post by JackT2000)
    How would I solve this?

    4x + y = 25
    x - 3y = 16

    None of the coefficients are the same so I dont know what to do?
    Change one of the equations to make one of the coefficients the same, and solve from there.*
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    Multiply one of the equations by a number to make one of the coefficients the same.
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    rearrange one of them for y then substitute that in the other, to get a value for x, then substitute that value into one of the equations to get y
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    In this case: y = 25 - 4x then sub this into the second equation and solve for x.
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    (Original post by JackT2000)
    How would I solve this?
    4x + y = 25
    x - 3y = 16
    Step 1:Make y the subject in both equations-
    First equation becomes:
    y=25-4x
    Second equation becomes
    -3y=16-x
    3y=-16+x
    3y=x-16
    y=(x-16)/3
    Step 2
    Equate the two equations and solve for x
    If y=25-4x and y also equals (x-16)/3
    Then 25-4x=(x-16)/3
    25-4x=(x-16)/3
    3(25-4x)=x-16
    75-12x=x-16
    Or x-16=75-12x
    x=75-12x+16
    x=91-12x
    x+12x=91
    13x=91
    x=91/13
    x=7
    Step 3:
    Use the solution for x to solve for y
    4x+y =25
    But x=7
    So4(7)+y=25
    28+y=25
    y=25-28
    y=(-)3
    Answers:
    x=7,
    y=(-)3
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    (Original post by JackT2000)
    How would I solve this?

    4x + y = 25
    x - 3y = 16

    None of the coefficients are the same so I dont know what to do?
    quickest way is just multiply the second equation by 4 then subtract equations
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    (Original post by 13 1 20 8 42)
    quickest way is just multiply the second equation by 4 then subtract equations
    I think multiplying the first by 3 and adding them would be faster than that
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    (Original post by RDKGames)
    I think multiplying the first by 3 and adding them would be faster than that
    I would prefer mine as I only have to do 39/13, instant, 91/13 one might think for half a second..then again I suppose there are more negatives to contend with
    In any case, the important thing is multiplying is faster than subbing for y
 
 
 
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