Question

х^2+9х+20=0, х^2+16х+28=0

Answer 1

х²+9х+20=0
a=1; b=9; c=20
D=b²-4ac
D= 9²-4×1×20= 81 - 80 = 1 больше нуля.
x1 = $frac{-b+d}{2a}$ = $frac{-9+1}{2}$ = $frac{-8}{2}$ = 4
x2 = -5