python二分法求立方根_用二分法求3的立方根的近似值（精确度为0.1）

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二分法:

1.4*1.4*1.4<3 1.5*1.5*1.5>3 取[1.4,1.5]

(1.4+1.5)/2=1.45 1.45^3=3.048625>3 取1.4 1.45

=1.425 =2.89… <3 取1.425 1.45

=1.4375 =2.97… <3 取1.4375 1.45

=1.44375 =3.0093.. >3 取1.4375 1.44375

=1.440625 =2.989… <3 取1.440625 1.44375

=1.4421875 =2.9996.. <3 取1.4421875 1.44375

excel实现:取[0,2]区间初值为1,公式为(3-x^3)/|(3-x^3)|*(1/n)+x其中e68a8462616964757a686964616f31333332643234n=2^(序号),1/n为区间宽度

或简单点取1.4或1.5为n初值,(3-n*n*n)/10+n慢慢接近3√3(3^1/3)

取初值2，利用EXCEL下拉计算得：(=(3-B:B*B:B*B:B)/10+B:B)

2.0000000000000000

1.5000000000000000

1.4625000000000000

1.4496849609375000

1.4450211286557200

1.4432882808137900

1.4426396324040100

1.4423961580101300

1.4423046742997900

1.4422702867090400

1.4422573589677800

1.4422524986216000

1.4422506712762000

1.4422499842434600

1.4422497259368800

1.4422496288201700

1.4422495923067300

1.4422495785786000

1.4422495734171700

1.4422495714766000

1.4422495707470000

1.4422495704726800

1.4422495703695500

1.4422495703307700

1.4422495703161900

1.4422495703107100

1.4422495703086500

1.4422495703078800

1.4422495703075800

1.4422495703074700

1.4422495703074300

1.4422495703074200

1.4422495703074100