2+x=2.5+0.4x-1.2
x-0.4x=2.5-1.2-2
0.6x=-0.7
x=-7/6
АВ=54мм-наклонная,AH=27√2мм-проекция
cosBAH=AH/AB=27√2/54=√2/2
<BAH=45гр
20*0-32=-32 (точка пересечения с Ох)
20х-32=0
20х=32
х=32/20=8/5 (точка пересечения с Оу)
√3sinx +cosx +2cos3x=0 , x∈[π ;3π/2]
2cos(x -π/3) +2cos3x =0 ;
cos3x+<span>cos(x -π/3) =0 ;
2cos(2x - </span>π/6)*cos(x +π/6) =0 ⇔[cos(2x - π/6)=0 ; cos(x +<span>π/6) =0.
</span>* * * cos(2x - π/6)=0 или cos(x +π/6) =0 * * *
[2x - π/6=π/2+π*n ; x +π/6 = π/2+π*n , n∈Z.
[x = π/3+<span>π*n/2 </span> ; x =π/3+π*n , n∈Z .
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x =π/3+π*n/2 ,n∈Z . ⇒x =π/3+π ∈[π ;3π/2] , если n =2 .<span>
x =</span>π/3+π*n , n∈Z . ⇒ x =π/3+π ∈[π ;3π/2] , если n =1 .
ответ: 4π/3.
* * *P.S. a*sinx +b*cosx =√(a²+b²) cos(x -ω) , где ctqω = b/a * * *
√3sinx +cosx =2*((1/2)*cosx +(√3/2)*sinx) =
2*(cosx*cosπ/3 +sinx*sinπ/3) = 2cos(x -π/3 )<span> .
</span>-------
π ≤ π/3+π*n/2 ≤ 3π/2⇔π - π/3 ≤ π*n/2 ≤ 3π/2 -π/3⇔
2π/3 ≤ π*n/2 ≤ 7π/6⇔ 4/3 ≤ n <span>≤ </span>7/3⇒ n=2.
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π ≤ π/3+π*n ≤ 3π/2⇔π - π/3≤ π*n ≤ 3π/2 -π/3⇔2π/3 ≤ π*n ≤ 4π/3<span>⇔
</span>2/3 ≤ n 4/3⇒ n=1
3.3 + 11.3 +q =0, 9+33+q=0, q= -42
3+x =-11, 3.x = -42
3-14 = -11, 3.(-14) = -42
Neznakomyj koren : -14