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sin3x+sin9x=0 equation

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Numerical solution:

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The solution

You have entered [src]
sin(3*x) + sin(9*x) = 0
$$\sin{\left(3 x \right)} + \sin{\left(9 x \right)} = 0$$
The graph
Sum and product of roots [src]
sum
  5*pi   2*pi   pi   pi   pi   pi   pi   pi   2*pi   5*pi     
- ---- - ---- - -- - -- - -- + -- + -- + -- + ---- + ---- + pi
   6      3     2    3    6    6    3    2     3      6       
$$\left(\left(\left(\left(\left(\left(\left(\left(\left(- \frac{5 \pi}{6} - \frac{2 \pi}{3}\right) - \frac{\pi}{2}\right) - \frac{\pi}{3}\right) - \frac{\pi}{6}\right) + \frac{\pi}{6}\right) + \frac{\pi}{3}\right) + \frac{\pi}{2}\right) + \frac{2 \pi}{3}\right) + \frac{5 \pi}{6}\right) + \pi$$
=
pi
$$\pi$$
product
  -5*pi -2*pi -pi  -pi  -pi  pi pi pi 2*pi 5*pi   
0*-----*-----*----*----*----*--*--*--*----*----*pi
    6     3    2    3    6   6  3  2   3    6     
$$\pi \frac{5 \pi}{6} \frac{2 \pi}{3} \frac{\pi}{2} \frac{\pi}{3} \frac{\pi}{6} \cdot - \frac{\pi}{6} \cdot - \frac{\pi}{3} \cdot - \frac{\pi}{2} \cdot - \frac{2 \pi}{3} \cdot 0 \left(- \frac{5 \pi}{6}\right)$$
=
0
$$0$$
0
Rapid solution [src]
x1 = 0
$$x_{1} = 0$$
     -5*pi
x2 = -----
       6  
$$x_{2} = - \frac{5 \pi}{6}$$
     -2*pi
x3 = -----
       3  
$$x_{3} = - \frac{2 \pi}{3}$$
     -pi 
x4 = ----
      2  
$$x_{4} = - \frac{\pi}{2}$$
     -pi 
x5 = ----
      3  
$$x_{5} = - \frac{\pi}{3}$$
     -pi 
x6 = ----
      6  
$$x_{6} = - \frac{\pi}{6}$$
     pi
x7 = --
     6 
$$x_{7} = \frac{\pi}{6}$$
     pi
x8 = --
     3 
$$x_{8} = \frac{\pi}{3}$$
     pi
x9 = --
     2 
$$x_{9} = \frac{\pi}{2}$$
      2*pi
x10 = ----
       3  
$$x_{10} = \frac{2 \pi}{3}$$
      5*pi
x11 = ----
       6  
$$x_{11} = \frac{5 \pi}{6}$$
x12 = pi
$$x_{12} = \pi$$
x12 = pi
Numerical answer [src]
x1 = -80.1106126488474
x2 = -21.9911485751286
x3 = -95.8185758710707
x4 = 70.162235930172
x5 = 38.2227106411424
x6 = 50.2654824574367
x7 = 54.4542726622231
x8 = -39.7935069454707
x9 = -14.1371670288058
x10 = -51.8362787064342
x11 = 48.1710873550435
x12 = -41.8879020478639
x13 = -73.8274272874554
x14 = 23.0383461263252
x15 = -100.007366131088
x16 = -5.75958652418445
x17 = 41.3643031809126
x18 = -78.0162175477172
x19 = -19.8967534727354
x20 = -25.6563400360841
x21 = 97.9129710722574
x22 = 18.3259571113714
x23 = 0.0
x24 = -3.66519146333868
x25 = -36.1283155471544
x26 = 43.9822971502571
x27 = -43.9822971502571
x28 = 16.2315620582544
x29 = 9.94837677192715
x30 = -12.0427718061402
x31 = -27.7507351061622
x32 = 75.9218224991565
x33 = 53.9306739246208
x34 = 34.0339203536073
x35 = -65.9734457253857
x36 = -87.9645943005142
x37 = -90.0589894029074
x38 = 26.1799387799149
x39 = 82.2050078081952
x40 = 7.85398156323863
x41 = -69.6386371711468
x42 = -56.0250689658707
x43 = 24.0855436775217
x44 = 87.9645943005142
x45 = -68.5914396168299
x46 = -63.8790506229925
x47 = 92.1533845053006
x48 = 56.0250689490422
x49 = 31.9395253488514
x50 = 14.6607657167524
x51 = -47.6474886059294
x52 = 72.2566310325652
x53 = -17.8023583703422
x54 = 40.3171056875068
x55 = 2.0943951023932
x56 = -60.7374579694027
x57 = -85.870199198121
x58 = 46.0766922526503
x59 = 62.3082542647397
x60 = 78.0162175408331
x61 = 73.8274272238026
x62 = -34.0339203853826
x63 = -42.4115008967313
x64 = 28.2743338823081
x65 = -71.733032268673
x66 = 94.2477796076938
x67 = 21.9911485751286
x68 = -15.707963267949
x69 = 12.0427717539012
x70 = -61.7846555205993
x71 = 65.9734457253857
x72 = -31.9395254400222
x73 = -81.157810257599
x74 = 4.18879020478639
x75 = -9.94837684908959
x76 = 60.2138592244649
x77 = -7.85398169885663
x78 = 100.007366129686
x79 = 6.28318530717959
x80 = 68.0678408277789
x81 = 86.3937980770007
x82 = -96.8657736141804
x83 = -28.2743338823081
x84 = -29.8451301356856
x85 = -93.7241808491601
x86 = 84.2994028428616
x87 = 80.1106127345707
x88 = 90.0589894029074
x89 = -58.1194640908306
x90 = -49.7418836876647
x91 = -83.7758040957278
x92 = -37.6991118430775
x93 = -91.6297857283069
x93 = -91.6297857283069