Matematika

Pertanyaan

bantuin dong please :)

dik. 2/x +3/y = 4
1/x-1/y = 1/2
tentukan. 1/(x+y)

2 Jawaban

  • 2/x + 3/y = 4    | kali 1|
    1/x - 1/y = 1/2  | kali 2|
    __________________ -
    3/y - (- 1/y) = 4 - (1/2)(2)
    4/y = 4 - 1
    4/y = 3
    y = 4/3
    susbtitusi:
    2/x + 3/(4/3) = 4
    2/x + 9/4 = 4
    2/x = 7/4
    x = 7/8

    maka: 1/(x + y)
    = 1/(4/3 + 7/8)
    = 1/(32/24 + 21/24)
    = 1/(53/24)
    = 24/53
  • (2/x +3/y =4)×1 =2/x+3/y=4 ⇒2/x+3/y-4=0
    (1/x-1/y=1/2)×2 =2/x-2/y=1 ⇒2/x-2/y-1=0

    (2/x+3/y-4)-(2/x-2/y-1)
    5/y-3⇒5/y=3
               y=5/3
    2/x+3/y=4
    2/x+3/(5/3)=4
    2/x+9/5=4
    2/x=4-9/5
    2/x=11/5
                x=10/11

    jadi 1/(x+y)=1/(10/11+5/3)
                     =1/(85/33
                     =33/85
                     =0,39

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