Вопрос:

1) 10x-11 = 4x - 7 2) 14x-25 = 20x + 9 3) -3(5-x) = 35-5x 4) 14x + 3 = 8x - 43 5) 18x + 9=32x + 14 6) 0,8(x - 2) + 2,6 = 0,5(7 + x) 7) -0,5(x - 4) - 7,3 = 0,8(2 – x) 8) (x+7)/(x+9) = 3/4 9) (x-7)/9 = (4-x)/7 11) 3/x-7 = 2/(4-x) 11) (1,2x-2)(8x + 5,6) = 0 12) (8y + 6)(1,8 – 0,4y) = 0

Ответ:

Решение уравнений:




  1. 10x - 11 = 4x - 7


    10x - 4x = 11 - 7


    6x = 4


    x = 4/6 = 2/3


    Ответ: x = 2/3




  2. 14x - 25 = 20x + 9


    14x - 20x = 25 + 9


    -6x = 34


    x = -34/6 = -17/3


    Ответ: x = -17/3




  3. -3(5 - x) = 35 - 5x


    -15 + 3x = 35 - 5x


    3x + 5x = 15 + 35


    8x = 50


    x = 50/8 = 25/4


    Ответ: x = 25/4




  4. 14x + 3 = 8x - 43


    14x - 8x = -3 - 43


    6x = -46


    x = -46/6 = -23/3


    Ответ: x = -23/3




  5. 18x + 9 = 32x + 14


    18x - 32x = 9 + 14


    -14x = 23


    x = -23/14


    Ответ: x = -23/14




  6. 0,8(x - 2) + 2,6 = 0,5(7 + x)


    0,8x - 1,6 + 2,6 = 3,5 + 0,5x


    0,8x + 1 = 3,5 + 0,5x


    0,8x - 0,5x = 3,5 - 1


    0,3x = 2,5


    x = 2,5 / 0,3 = 25/3


    Ответ: x = 25/3




  7. -0,5(x - 4) - 7,3 = 0,8(2 – x)


    -0,5x + 2 - 7,3 = 1,6 - 0,8x


    -0,5x - 5,3 = 1,6 - 0,8x


    -0,5x + 0,8x = 1,6 + 5,3


    0,3x = 6,9


    x = 6,9 / 0,3 = 69/3 = 23


    Ответ: x = 23




  8. \[ \frac{x+7}{x+9} = \frac{3}{4} \]


    4(x+7) = 3(x+9)


    4x + 28 = 3x + 27


    4x - 3x = 27 - 28


    x = -1


    Ответ: x = -1




  9. \[ \frac{x-7}{9} = \frac{4-x}{7} \]


    7(x-7) = 9(4-x)


    7x - 49 = 36 - 9x


    7x + 9x = 36 + 49


    16x = 85


    x = 85/16


    Ответ: x = 85/16




  10. \[ \frac{3}{x-7} = \frac{2}{4-x} \]


    3(4-x) = 2(x-7)


    12 - 3x = 2x - 14


    12 + 14 = 2x + 3x


    26 = 5x


    x = 26/5


    Ответ: x = 26/5




  11. (1,2x - 2)(8x + 5,6) = 0


    1,2x - 2 = 0 или 8x + 5,6 = 0


    1,2x = 2 или 8x = -5,6


    x = 2 / 1,2 = 20/12 = 5/3 или x = -5,6 / 8 = -56/80 = -7/10


    Ответ: x = 5/3; x = -7/10




  12. (8y + 6)(1,8 – 0,4y) = 0


    8y + 6 = 0 или 1,8 - 0,4y = 0


    8y = -6 или 1,8 = 0,4y


    y = -6/8 = -3/4 или y = 1,8 / 0,4 = 18/4 = 9/2


    Ответ: y = -3/4; y = 9/2