-0,7х+2=65
-0,7х=65-2
-0,7х=63
х= -90
Ответ: -90.
2^(x-1)+2^(x-2)+2^(x-3)=448
2^x *2⁻¹+2^x*2⁻²+2^x*2⁻³=448
2^x*(1/2)+2^x*(1/4)+2^x*(1/8)=448
2^x*(1/2+1/2+1/8)=448
2^x*(7/8)=448
2^x=448:(7/8)
2^x=512
2^x=2⁹
<u>x=9</u>
3(2х-3у)...................
( Х - 1 )^2 - 16 = 0
( x - 1 )^2 - 4^2 = 0
( x - 1 + 4 )( x - 1 - 4 ) = 0
( x + 3 )( x - 5 ) = 0
X + 3 = 0 ; x = - 3
X - 5 = 0 ; x = 5
Ответ ( - 3 ) ; 5