Răspuns:
(2x+3)²-(x-3)(x+7)-2(x-2)²
Explicație pas cu pas:
(2x+3)²= (2x)²+12x+9=4x²+12x+9
(x-3)(x+7)= x²+7x-3x-21=x²+4x-21
-2(x-2)²=-2(x²-4x+4)=-2x²+8x-8
4x²+12x+9-x²+4x-21-2x²+8x-8=x²+24x-20
x²+24x-20=0
Δ= b²-4ac
Δ= 24²-4*1*(-20)
Δ= 576 +80
Δ= 656
x1= -24+√656/2= -24+2√164/2
x2= -24-√656/2= -24-2√164/2
