Найдите значение выражения 2/3m-7/12m-5/6m-3/4m при m= 1)-0,9 2)26/27 3)-52

2/3m - 7/12m - 5/6m - 3/4m.

1) Найдем значение выражения при m = -0,9:

2/3 * (-9/10) - 7/12 * (-9/10) - 5/6 * (-9/10) - 3/4 * (-9/10) = (-2/3) * (3 * 3)/(2 * 5) + (7/(3 * 4)) * ((3 * 3)/10) + (5/(3 * 2)) * (3 * 3)/(5 * 2) + 3/4 * 9/10 = -3/5 + 7/40 + 3/2 + 27/40 = -3/5 + 3/2 + 34/40 = -6/10 + 15/10 + 17/20 = 9/10 + 17/20 = 18/20 + 17/20 = 35/20 = 1 15/20 = 1 3/4.

2) при m = 26/27:

2/3 * 26/27 - 7/12 * 26/27 - 5/6 * 26/27 - 3/4 * 26/27 = (2 * 26)/(3 * 27) - (7 * 2 * 13)/(2 * 6 * 27) - (5 * 2 * 13)/(2 * 3 * 27) - (3 * 2 * 13)/(2 * 2 * 3 * 9) = 52/81 - 91/162 - 65/81 - 13/18 = -13/81 - 91/162 - 13/18 = -26/162 - 91/162 - 13/18 = -117/162 - 117/162 = -234/162 = -13/9 = - 1 4/9.

3) при m = -52:

2/3 * (-52) - 7/12 * (-52) - 5/6 * (-52) - 3/4 * (-52) = -104/3 + (7 * 4 * 13)/(3 * 4) + (5 * 2 * 26)/(3 * 2) + (3 * 4 * 13)/4 = -104/3 + 91/3 + 130/3 + 39 = 117/3 + 39 = 39 + 39 = 78.