9x-18=0
9x=0+18
9x=18
x=18:9
x=2
x²+7x-18=0
D = b² - 4ac = 7²-4*1*(-18)= 49+72=121
x1= -b+√D/2a = -7+11/2= 2
x2= -b -√D/2a = -7-11/2= -9
ответ: x1=2, x2= -9
9x-18=0
9x=0+18
9x=18
x=18:9
x=2
x²+7x-18=0
D = b² - 4ac = 7²-4*1*(-18)= 49+72=121
x1= -b+√D/2a = -7+11/2= 2
x2= -b -√D/2a = -7-11/2= -9
ответ: x1=2, x2= -9