1)2 2/7=16/7
-2,6= -13/5
-13/5*16/7=-208/35
3,5=7/6
-208/35*7/6=-1456/210х
4/13*(-39/10)=-156/130
3,25=13/4
-156/130*13/4=-2028/520=-3,9
-3,9*4=-15,6
-1456/210х=-15,6
х=(-156/10)/(-1456/210)
х=2,25
1) -2х+1+5(х-2)=-4(3-х)+1
-2x+1+5x-10 = -12+4x+1
3x-9 = 4x-11
4x-3x = 11-9
x = 2
2) (х-5)^2 +(х+4)^2=2х^2
x^2-10x+25 +x^2+8x+16 = 2x^2
-2x+41= 2x^2 - 2x^2
2x = 41
x = 41/2
x =20,5
<span>3) 5+ х/2=3x+6/5
5+ 0,5x =3x +1,2
2,5x = 3,8
x = 3,8/2,5
x = 1,52</span>
Log4(2-x)=log4(25)/log4(16)
log4(2-x)=log4(25)/2
log4(2-x)=1/2log4(25)
log4(2-x)=log4(25)^1/2
log4(2-x)=log4(5)
2-x=5
x=-3
Ответ: -3.