1) 5х + 10 = 15х + 40 2) 2(-5х + 10) = 8
5х - 15х = 40 - 10 -5х + 10 = 8 : 2
-10х = 30 -5х + 10 = 4
х = 30 : (-10) -5х= 4 - 10
х = -3 -5х = -6
х = -6 : (-5)
х = 1,2
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
-3 + 1,2 = -1,8 - сумма корней уравнений
Вiдповiдь: (-1,8).
Пошаговое объяснение:
306.
а)
1) 14/15 + 2 1/2 + 0,3 =
14/15 + 2 1/2 + 3/10 =
28/30 + 2 15/30 + 9/30 =
2 52/30 = 3 22/30 = 3 11/15
2) 3 11/15 * 8/7 = 56/15 * 8/7 = 8/15 * 8/1 = 64/15
3) 64/15 * 3/4 = 16/5 * 1/1 = 16/5 = 3,2
4) 3,2 + 0,5 = 3,7 или 3. 7/10
б)
1) 0,5 + 1/8 - 1/6 =
5/10 + 1/8 - 1/6 = 1/2 + 1/8 - 1/6 = 12/24 + 3/24 - 4/24 = 11/24
2) 6,4 : 26 2/3 = 6 4/10 : 26 2/3 = 6 2/5 : 26 2/3 = 32/5 : 80/3 = 32/5 * 3/80 = 2/5 * 3/5 = 6/10 = 3/5
3) 11/24 * 3/5 = 11/8 * 1/5 = 11/40
4) 11/40 + 0,125 = 0,275 + 0,125 = 0,4 или 4/10 = 2/5
307
а)
1) 3 2/5 - 1 7/40 = 3 16/40 - 1 7/40 = 2 9/40
2) 4 * 2 9/40 = 4 * 89/40 = 1*89 / 10 = 89/10 = 8 9/10
3) 12,5 : 6 1/4 = 12 5/10 : 6 1/4 = 12 1/2 : 6 1/4 = 25/2 : 25/4 = 25/2 * 4/25 = 4/2 = 2
4) 8 9/10 + 2 + 3 = 13 9/10
б)
1) 2,5 - 1 7/8 = 2,5 - 15/8 = 2,5 - 1,875 = 0,625
2) 0,625 : 1/8 = 0,625 : 0,125 = 5
3) 2 3/4 - 1,5 = 11/4 - 1,5 = 2,75 - 1,5 = 1,25
4) 1,25 + 5 - 0,25 = 6
