After homing in on the areas of interest:
For x = -7 To 6 Step 0.0001
f = x * Int(x * Int(x * Int(x)))
If Int(f + 0.5) = 2020 Then
Text1.Text = Text1.Text & x & Str(f) & vbCrLf
End If
DoEvents
Next
For x = 6.999 To 7.001 Step 0.0001
f = x * Int(x * Int(x * Int(x)))
' If Int(f + 0.5) = 2020 Then
Text1.Text = Text1.Text & x & Str(f) & vbCrLf
' End If
DoEvents
Next
produces
-6.6245 2020.4725
-6.6244 2020.4420
-6.6243 2020.4115
-6.6242 2020.3810
-6.6241 2020.3505
-6.6240 2020.3200
-6.6239 2020.2895
-6.6238 2020.2590
-6.6237 2020.2285
-6.6236 2020.1980
-6.6235 2020.1675
-6.6234 2020.1370
-6.6233 2020.1065
-6.6232 2020.0760
-6.6231 2020.0455
-6.6230 2020.0150
-6.6229 2019.9845
-6.6228 2019.9540
-6.6227 2019.9235
-6.6226 2019.8930
-6.6225 2019.8625
-6.6224 2019.8320
-6.6223 2019.8015
-6.6222 2019.7710
-6.6221 2019.7405
-6.6220 2019.7100
-6.6219 2019.6795
-6.6218 2019.6490
-6.6217 2019.6185
-6.6216 2019.5880
-6.6215 2019.5575
-6.6214 2019.5270
6.9990 2001.714
6.9991 2001.7426
6.9992 2001.7712
6.9993 2001.7998
6.9994 2001.8284
6.9995 2001.857
6.9996 2001.8856
6.9997 2001.9142
6.9998 2001.9428
6.9999 2001.9714
7 2002
7.0001 2401.0343
7.0002 2401.0686
7.0003 2401.1029
7.0004 2401.1372
7.0005 2401.1715
7.0006 2401.2058
7.0007 2401.2401
7.0008 2401.2744
7.0009 2401.3087
7.0010 2401.3430
showing the positive side skips over 2020.
The negative side is near -6.623; floor(x*floor(x*floor(x))) is an integer near
2020 / -6.623
That integer must be -305
2020 = x * -305
As x must be rational (since both 2020 and [...] are integers)
x = -2020/305 = -404/61 ~= -6.62295081967213
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Posted by Charlie
on 2020-09-15 13:54:23 |
the graph and table method
