El profesor se sorprenderá mucho al ver tu solución correcta😉
/ pi\ cos|3*x - --| = -1 \ 7 /
suma
2*pi 8*pi - ---- + ---- 7 21
=
2*pi ---- 21
producto
-2*pi 8*pi -----*---- 7 21
=
2 -16*pi ------- 147
-16*pi^2/147
-2*pi x1 = ----- 7
8*pi x2 = ---- 21
x2 = 8*pi/21
x1 = 28.4239334356559
x2 = 7.47998266059111
x3 = -7.18078333293411
x4 = -15.5583637220837
x5 = -11.369573571314
x6 = 93.3501817171013
x7 = 84.9726016218431
x8 = -80.4846116297185
x9 = -65.823846001601
x10 = 15.8575630187885
x11 = 49.3678846050735
x12 = -9.27517847070243
x13 = -49.0686851646588
x14 = -51.1630804683869
x15 = -1368.53759990314
x16 = -53.2574756181414
x17 = 61.9342552283596
x18 = -49.0686852465977
x19 = 99.6333671801585
x20 = -78.3902165213399
x21 = 47.2734891047299
x22 = 80.7838109475101
x23 = -76.2958214328808
x24 = 78.6894158275889
x25 = -34.4079193704178
x26 = 17.9519580654927
x27 = -26.0303390990447
x28 = -93.050982230248
x29 = 22.1407483709445
x30 = -97.2397727641814
x31 = 20.0463530339909
x32 = 59.8398601771578
x33 = 13.7631679537253
x34 = -28.124734140167
x35 = -74.2014263591347
x36 = -55.3518707236266
x37 = 40.990304565397
x38 = -23.9359442004782
x39 = 51.4622798032678
x40 = 72.4062305937654
x41 = -38.5967096440199
x42 = -36.5023144838375
x43 = 1.19679729759992
x44 = -30.2191292024656
x45 = -2.99199342521284
x46 = -42.7854996560803
x47 = 64.0286502292904
x48 = 55.6510700277376
x49 = 34.707118677928
x50 = 97.538972077654
x51 = 91.255786185354
x52 = -57.4462658083151
x53 = -84.6734020574456
x54 = 36.8015138059384
x55 = 5.38558748389324
x56 = 11.6687728747392
x57 = 38.8959090246274
x58 = -21.8415488211677
x59 = 26.329538379627
x60 = 3.29119207098569
x61 = 95.4445769437861
x62 = -59.540660879452
x63 = -5.08638807798786
x64 = -19.7471538246632
x65 = -82.5790067769536
x66 = 32.6127235816343
x67 = -111.900538341804
x68 = 24.2351433391924
x69 = 53.5566749291615
x70 = -99.3341678752414
x71 = -17.6527587802157
x72 = -70.0126362659696
x73 = -13.4639686531083
x74 = -95.1453775994245
x75 = 70.3118355399575
x76 = -63.7294509873553
x77 = 82.8782061389394
x78 = -72.1070312997776
x79 = 76.595020735167
x80 = 74.5006256586098
x81 = -61.6350559396189
x82 = 30.5183285025402
x83 = -40.6911049816937
x84 = 68.2174405046505
x85 = 57.7454651094393
x86 = 9.57437777977355
x87 = -32.3135242788081
x87 = -32.3135242788081