Question

用二分法求得函数f(x)=x^3+2x++3x+4在(-2,-1)上的零点,求详解

Answer 1

a c=(a+b)/2 b c^3+2c^2+3x+4
-2 -1.5 -1 1.625 >0 b取c a不变
-2 -1.75 -1.5 0.515625
-2 -1.875 -1.75 -0.185546875 <0 a取c 不变
-1.875 -1.8125 -1.75 0.178466797
-1.875 -1.84375 -1.8125 -9.15527E-05
-1.84375 -1.828125 -1.8125 0.0900383
-1.84375 -1.8359375 -1.828125 0.045187473
-1.84375 -1.83984375 -1.8359375 0.022601664
-1.84375 -1.841796875 -1.83984375 0.011268504
-1.84375 -1.842773438 -1.841796875 0.00559184
-1.84375 -1.843261719 -1.842773438 0.002750985
-1.84375 -1.843505859 -1.843261719 0.001329927
-1.84375 -1.84362793 -1.843505859 0.00061924
-1.84375 -1.843688965 -1.84362793 0.000263857
-1.84375 -1.843719482 -1.843688965 8.61552E-05
-1.84375 -1.843734741 -1.843719482 -2.69793E-06
-1.843734741 -1.843727112 -1.843719482 4.17289E-05
-1.843734741 -1.843730927 -1.843727112 1.95155E-05
-1.843734741 -1.843732834 -1.843730927 8.4088E-06
-1.843734741 -1.843733788 -1.843732834 2.85544E-06
-1.843734741 -1.843734264 -1.843733788 7.87537E-08
-1.843734741 -1.843734503 -1.843734264 -1.30959E-06
-1.843734503 -1.843734384 -1.843734264 -6.15418E-07
-1.843734384 -1.843734324 -1.843734264 -2.68332E-07
-1.843734324 -1.843734294 -1.843734264 -9.47891E-08
-1.843734294 -1.843734279 -1.843734264 -8.0177E-09
-1.843734279 -1.843734272 -1.843734264 3.5368E-08
-1.843734279 -1.843734276 -1.843734272 1.36751E-08
-1.843734279 -1.843734277 -1.843734276 2.82872E-09
-1.843734279 -1.843734278 -1.843734277 -2.59449E-09

Answer 2

题目是不是打错了，两个加号