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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 7: 1)x-3/5-x=5/7 2)x-2/x-1=x+4/x+7 3(0,52 :x)=9,63:16,38

Tháng Mười Một 12, 2022 Toán học 2 Comments 0 views

Toán Lớp 7: 1)x-3/5-x=5/7
2)x-2/x-1=x+4/x+7
3(0,52 :x)=9,63:16,38

Comments ( 2 )

  1. maitrucloan
    maitrucloan
    12 Tháng Mười Một, 2022 at 8:45 sáng
    Reply
    1)
    (x-3)/(5-x)=5/7    ĐK : x ne 5
    to 7(x-3)=5(5-x)
    to 7x-21=25-5x
    to 7x+5x=25+21
    to 12x=46
    to x=23/6 \ \ text{(tm)}
    Vậy x=23/6
    2)
    (x-2)/(x-1)=(x+4)/(x+7)    ĐK : x ne 1;-7
    to (x-2)(x+7)=(x+4)(x-1)
    to x^2+5x-14=x^2+3x-4
    to x^2-x^2+5x-3x=-4+14
    to 2x=10
    to x=5 \ \ text{(tm)}
    Vậy x=5
    3)
    0,52 : x = 9,63 : 16,38   ĐK : x ne 0
    to (0,52)/x = (9,63)/(16,38)
    to (0,52)/x = 107/182
    to 107x=182.0,52
    to 107x=94,64
    to x=2366/2675 \ \ text{(tm)}
    Vậy x=2366/2675

  2. doanthulan
    doanthulan
    12 Tháng Mười Một, 2022 at 8:45 sáng
    Reply
    $\\$
    1,
    (x-3)/(5-x)=5/7 (x\ne 5)
    -> (x-3) . 7 = (5-x) . 5
    -> 7x-21=-5x + 25
    ->7x +5x=21+25
    -> 12x=46
    ->x=46 : 12
    ->x=23/6 (Thỏa mãn)
    Vậy x=23/6
    $\\$
    2,
    (x-2)/(x-1) = (x+4)/(x+7) (x \ne 1, x \ne -7)
    -> (x-2) . (x+7) = (x-1) . (x+4)
    -> x (x+7)-2 (x+7) = x (x+4)-1 (x+4)
    ->x^2 + 7x – 2x – 14= x^2 + 4x – x – 4
    ->  x^2 + 5x-14 =x^2 + 3x-4
    ->x^2 +5x-14-x^2-3x +4=0
    -> (x^2-x^2) + (5x-3x)+(-14+4)=0
    -> 2x-10=0
    ->2x=0+10
    ->2x=10
    ->x=10:2
    ->x=5 (Thỏa mãn)
    Vậy x=5
    $\\$
    3,
    0,52 : x=9,63 : 16,38
    -> 0,52 : x=107/182
    ->x=0,52 : 107/182
    ->x=2366/2675
    Vậy x=2366/2675

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222-9+11+12:2*14+14 = ? ( )

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