Question

BOS.SE
B) x2 + 8x + 7 = 0;
T) x2 – 19x + 18 = 0.
B) x2 - 9x - 10 = 0;
r) x2 + 8x - 9 = 0.
10

Answer 1

1) D = 3
x = -1; -7
2) D = 17
x = 1; 18
3) D = 11
x = -1; 10
4) D = 5
x = 1; -9

Answer 2

Ответ:

$1)\ \ x^2+8x+7=0\ \ ,\ \ x_1=-7\ ,\ x_2=-1\ \ (teorema\ Vieta)\\\\-7\cdot (-1)=7\ \ ,\ \ \ -7+(-1)=-8\\\\2)\ \ x^2-19x+18=0\ \ ,\ \ x_1=1\ ,\ x_2=18\ \ (teorema\ Vieta)\\\\1\cdot 18=18\ \ ,\ \ 1+18=19\\\\3)\ \ x^2-9x-10=0\ \ ,\ \ x_1=-1\ ,\ x_2=10\ \ (teorema\ Vieta)\\\\-1\cdot 10=-10\ \ ,\ \ -1+10=9\\\\4)\ \ x^2+8x-9=0\ \ ,\ \ x_1=-9\ ,\ x_2=1\ \ (teorema Vieta)\\\\-9\cdot 1=-9\ \ ,\ \ -9+1=-8$