3x - 4x = 2 + 1
- x = 3
x = - 3
<span>sin(π/2+2x)ctg3x+sin(π+2x)-√2cos5x=0
cos2x *cos3x/sin3x -sin2x-√2cos5x=0
(cos2xcos3x-sin2xsin3x-√2cos5xsin3x)/sin3x=0
</span><span>cos2xcos3x-sin2xsin3x-√2cos5xsin3x=0 U sin3x≠0
cos(3x+2x)-</span>√2cos5xsin3x=0
cos5x-<span>√2cos5xsin3x=0
cos5x(1-√2sin3x)=0
cos5x=0⇒5x=π/2+πn⇒x=π/10+πn/5
sin3x=1/√2⇒3x=(-1)^n *π/4+πn⇒x=</span><span>(-1)^n *π/12+πn</span>/3
(4x+5y)²=9y
(4x+5y)²<span>=9x
16x</span>²+20xy+25y²=9y
16x²+20xy+25y²=9x
9y=9x
y=x
Cos²(π/4+a)=(1+cos(π/2+2a)/2=(1-sin2a)/2
cos²(a-π/4)=(1+cos(2a-π/2))/2=(1+sin2a)/2
cos²(π/4+a)-cos²(a-π/4)=(1-sin2a)/2-(1+sin2a)/2=(1-sin2a-1-sin2a)/2=-2sin2a/2=-sin2a
Х²-у²=(х+у)(х-у)=-5(х-у)=13⇒ х-у=-2.6
и х+у=-5 сложим эти уравнения 2х=-7.6⇒ х=-3.8
теперь вычтем -2у=2.4⇒у=-1.2