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<span> х(4х + 5) - 7(4х +5) = 0
(х - 7)(4х + 5) = 0
х - 7 = 0 или 4х + 5 = 0
х = 7 4х = -5
х = -1,25
Ответ: х=-1,25; х = 7</span>
Sin3x=cos3x|:cos3x≠0
tg3x=1
3x=П/4+Пn, n∈Z
x=П/12+Пn/3, n∈Z
[0;4]
x1=П/12+П*0/3=П/12∉[0;4]
x2=П/12+П*1/3=П/12+4П/12=5П/12∈[0;4]
x3=П/12+П*2/3=П/12+8П/12=9П/12∈[0;4]
x3=П/12+П*3/3=П/12+12П/12=13П/12∈[0;4]
x4=П/12+П*4/3=П/12+16П/12=17П/12∉[0;4]
Ответ: 5П/12; 9П/12; 13П/12
9/х - 9х/5х = 9/х - 9/5
х = -2; 9/(-2) - 9/5 = -(9/2 + 9/5) = - ((9*5 + 9*2)/10) = - 63/10 = -6,3