2cos(квадрат)2x + cos2x + cos6x = 1

2cos²2x-1+cos2x+cos6x=0 cos2(2x)+cos2x+cos6x=0 cos4x+cos2x+cos6x=0 cos4x+2*cos(6x+2x)/2*cos(6x-2x)/2=0 cos4x+2cos4x*cos2x=0 cos4x(1+2cos2x)=0 cos4x=0 4x=π*n/2 x=π*n/8 1+2cos2x=0 2cos2x=-1 cos2x=-1/2 2x=2π/3+2πn x=π/3+πn 2x=4π/3+2πn x=2π/3+πn

а) 3а+6b

3(a+2b)

 

б) 2x-8y

2(x-4y)

 

в) 8a+24b-12

4(2a+6b-3)

 

г) -49y-14y-63

-7(7y+2y+9)

 

д) 36p-24q+54

6(6p-4q+9)

 

pusti budet x i y storoni preamougolinovo

{2x+2y=26,x*y=36

{x+y=13,x*y=36

{x=13-y,(13-y)y=36

{x=13-y,13y-y^2=36

{x=13-y,y^2+13y-36=0

y^2+13y-36=0

d=169-4*1*(-36)=25

y1=-13-5/2=-9

y2=-13+5/2=4

{x=13-4=9,y=4

otvet: storoni preamougolinika rovni 4 cm i 9 cm