Odpowiedzi

2009-09-30T16:39:24+02:00
-(x+7)(x-3)= -(x²-3x+7x-21)=-x²+3x-7x+21=-x²-4x+21
2009-09-30T16:42:25+02:00
-(x+7)(x-3)= -x do kwadratu + 3x - 7x +21 = -x do kwadratu -4x +21
2009-09-30T16:45:49+02:00
-(x+7)(x-3)=
=(-x-7)(x-3)=
=-x²+9x-7x+21=
=-x²+2x+21

Δ=b²-4ac
Δ=4+42=46
√Δ=√46=√(4*12)=2√6

x1=(-2-2√6)/(-2)
x1=1+√6

x2=(-2+2√6)/(-2)
x2=1-√6