Question

найдите корень уравнения: х2+7х-18=0

Answer 1

9x-18=0

9x=0+18

9x=18

x=18:9

x=2

Answer 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