1)sin5x cos3 x+cos5x sin3x = sin8x
sin(5x+3x)=sin8x
sin8x=sin8x
2)cos5x cos3x - sin5x sin3x = cos8x
cos(5x+3x)=cos8x
cos8x=cos8x
Q=1/(3)^2
b1=3^3
bn=b1*q^(n-1)
b7=3^3*(3^-2)^6=3^3*3^-12=3^-9=1/3^9
X^4 - 10x^2 + 25 = 0
(x^2 - 5)^2 = 0
x^2 - 5 = 0
x^2 = 5
x = ± √5
0,8х*125у^3+ 4х^3*у^4 - ху^2*4x^2*у^2= 100ху^3+ 4х^3у^4 - 4х^3у^4 = 100х*у^3= 100*(-16)*(1/4)^3= 100*(-16)*(1/64)= -1600/64= -25
3х+2у=-4
х+4у=-18
3*(-18-4у)+2у=-4
х+4у=-18
-54-12у+2у=-4
х+4у=-18
-10у=50
х+4у=-18
у=-5
х+4у=-18
3х+2*(-5)=-4
х+4у=-18
3х-10=-4
х+4у=-18
3х=6
х+4у=-18
х=2
Ответ: х=2; у=-5