X^2 + 2x - 15 = 0
D = в^2 - 4ac = 4 + 4 * 1 * 15 = 4 + 60 = 64
x = (-2 +/- 8) / 2
x1 = -5
x2 = 3
...............=7
1) 4 5/12 - 3 13/24=4 10/24 - 3 13/24=21/24=7/8
2) 3 1/8 : 7/8=25/8 * 8/7=25/7
3) 25/7 : 4/7=25/7 * 7/4=25/4=6 1/4
4) 3 1/18 - 2 7/12=3 2/36 - 2 21/36=17/36
5) 17/36 * 1 10/17=17/36 * 27/17=3/4
6) 6 1/4+3/4=7
1)× + ×
2)+ × (+)
3)+ + ×
4)+ (-) +
5) + (× +)
6)+ (-) ×