The teacher will be very surprised to see your correct solution 😉
/x pi\ sin|- + --| = -1 \3 18/
-5*pi x1 = ----- 3
13*pi x2 = ----- 3
x2 = 13*pi/3
sum
5*pi 13*pi - ---- + ----- 3 3
=
8*pi ---- 3
product
-5*pi 13*pi -----*----- 3 3
=
2 -65*pi ------- 9
-65*pi^2/9
x1 = -99.4837702451178
x2 = 70.1622346562496
x3 = 70.1622373962342
x4 = -61.7846565105811
x5 = -99.4837659692826
x6 = -80.6342110919223
x7 = -5.23598846337339
x8 = -5.23598802448246
x9 = 13.6135690415039
x10 = 70.1622360280877
x11 = 51.3126794910504
x12 = 51.3126787396147
x13 = -24.0855450675216
x14 = 32.4631213181673
x15 = 89.0117914967097
x16 = -80.6342129617026
x17 = 32.4631255231335
x18 = 13.6135692374962
x19 = 51.3126803832776
x20 = 70.1622350570105
x21 = 13.6135666870516
x22 = -99.4837668751494
x23 = 89.0117906740962
x24 = 13.6135702642396
x25 = 32.463124832646
x26 = -42.9350997355404
x27 = -42.935098349142
x28 = -80.6342127262422
x29 = -99.4837666401773
x30 = -80.6342106151371
x31 = -99.4837659119862
x32 = 13.6135675174231
x33 = 51.3126815568832
x34 = 89.0117921626959
x35 = -5.23598624918
x36 = -24.085542714959
x37 = 51.3126811818992
x38 = 32.463123030893
x39 = -80.6342109289082
x40 = -24.0855444513601
x41 = -42.9350980578904
x42 = -42.9351007935127
x43 = 70.1622367973115
x44 = 32.4631225777541
x45 = -80.6342098945046
x46 = -80.6342102861259
x47 = 6554.40947713682
x48 = -42.9350997871399
x49 = 13.6135668155749
x50 = -24.0855436047653
x51 = 89.0117915921671
x52 = 89.0117923619355
x53 = 51.3126784833101
x54 = -24.0855421731002
x55 = 32.4631254934077
x56 = 51.3126806260284
x57 = -80.6342104205738
x58 = 107.861351429411
x59 = -5.23598885133824
x60 = -24.0855398847336
x61 = -61.784656763105
x62 = -99.4837675134227
x63 = 13.6135697015054
x64 = -24.0855425159028
x65 = 70.1622372452464
x66 = 32.463124570374
x67 = 32.4631239639637
x68 = -5.23598929110112
x69 = -80.6342119830858
x70 = 89.0117903107836
x71 = 89.0117931171951
x72 = 89.0117914689468
x73 = -61.7846554920137
x74 = 51.3126804228802
x75 = -61.7846564145052
x76 = -24.0855450966611
x77 = -5.23598713749819
x78 = -5.23598913593662
x79 = -61.7846540640803
x80 = 32.4631230991761
x81 = 89.0117933890366
x82 = -99.4837696384033
x83 = -61.7846569954863
x84 = -42.9350991124378
x85 = -5.23598642220758
x86 = -61.7846546744869
x87 = 32.4631208538596
x88 = 70.1622344640687
x89 = -42.9351011391729
x90 = -42.9351000059199
x91 = 13.6135683990585
x92 = -61.7846541796602
x92 = -61.7846541796602