1)х2^+2х-15=0 2)х2^-5х-14=0 3)х2^+3х-18=0

1) X^2 + 2X - 15 = 0 D = 4 - 4*1(-15) = 64   V D = 8 X1 = -2 + 8 \ 2 = 6\2 = 3 X2 = - 2-8\2 = -10\2 = - 5 ............................ 2) X^2 - 5X - 14 = 0 D = 25 -4*1*(-14) = 25 + 56 = 81  V D = 9 X1 = 5 + 9 \ 2 = 14 \ 2 = 7 X2 = 5 - 9 \ 2 = - 4 \ 2 = - 2 ................................... 3) X^2 + 3X - 18 = 0 D = 9 - 4*1*(-18) = 9 + 72 = 81 X1 = - 3 + 9 \ 2 = 6\2 = 3 X2 = - 3 - 9 \ 2 = - 12\2 = -6