X2+2x-7=0 help me please

Question

X2+2x-7=0 help me please

Answer 1

x²+2x-7=0

ax²+bx+c=0

D=b²-4ac

a=1, b=2, c=-7

D=2²-4×1×(-7)

D=4-4×(-7)

D=4+28

D=32

x(1,2)=-b+-~D/2a

~ - корень

x(1,2)=-2+-~32/2

x(1)=-2+4~2/2=2+2~2

~32=~16×2=~16×~2=4~2

x(2)=-2-4~2/2=2-2~2