1) - 4,81 * (-2,3) - (-2,3) * 5,19 = (-3/8+2 1/16) * 16 = - 3/8 * (-6,81) + (3,19) * (-3/8) = (-5/12+3/7) * 8,4 = 2) (x+4) * (x-3) = 0 (3/8y-9/16) * (y-0,8) = 0

а)

1. - 4,81 * ( - 2,3) + 2,3 * 5,19 = 11,063 + 11,937 = 23.

2. ( - 3/8 + 2 1/16) * 16 = 13.

2 1/16 = (2 * 16 + 1) / 16 = 19/16.

1: - 3/8 + 19/16 = - 6/16 + 19/16 = 13/16.

2: 13/16 * 16 = 208/16 = 13.

3. - 3/8 * ( - 6,81) + (3,19) * ( - 3/8) = - 3/8 * (3,19 - 6,81) = - 3/8 * ( - 3,62) = 1,3575.

4. ( - 5/12 + 3/7) * 8,4 = 1/10.

8,4 = 8 4/10 = 84/10

1: - 5/12 + 3/7 = - 35/84 + 36/84 = 1/84.

2: 1/84 * 84/10 = 84/840 на 84 = 1/10.

б)

1. (x + 4) * (x - 3) = 0

х + 4 = 0, х = - 4; х - 3 = 0, х = 3.

2. (3/8y - 9/16) * (y - 0,8) = 0

1: 3/8y - 9/16 = 0, 3/8y = 9/16, y = 9/16 / 3/8 = (9 * 8) / (16 * 3) = 72/48 на 24 = 3/2 = 1 1/2.

2: y - 0,8 = 0, у = 0,8.