写出方程x²-2x-4=0的近似解,精确到0.1

写出方程x²-2x-4=0的近似解,精确到0.1
写出方程x²-2x-4=0的近似解,精确到0.1

写出方程x²-2x-4=0的近似解,精确到0.1
x²-2x-4=0
(x-1)²=3
x-1=1.732或-1.732
x=2.732或-0.732
精确到0.1后,得
x=2.7或-0.7

x1=(2+根号（4+16))/2
X1=1+2.2
X1=3.2
X2=1-2.2
X2=-1.2

(x-1)^2=3 即x=1±1.732 所以x=2.7或是-0.7

f(3)=-1<0
f(4)>0
f(3.5)>0
f(3.25)>0
f(3.125)<0
f(3.1875)<0
f(3.21875)<0


近似解 =3.2( 1decimal place )

x²-2x-4=x²-2x+4-4-4=（x-2）²-8=0，得：x-2=2*2^(1/2)=2*1.4=2.8，x=4.8，或x-2=-2*2^(1/2)=-2*1.4=-2.8，x=0.8。所以，方程x²-2x-4=0的近似解为x=4.8，或x=0.8。