1)2(x+5)-4(x-3)=21-x
2x+10-4x+12=21-x
+10+12-21=+x
x=1
2)√3+I1-√3I + I√2 -4 I=
=√3-1+√3 -√2 +4 =
=2√3-√2+3
3) [(2³⁰)⁰ -(2⁰)³⁰] : (15/4)¹⁹⁹⁴=(1-1):(15/4)¹⁹⁹⁴=0:(15/4)¹⁹⁹⁴=0
5 a/8=b/1 at 4a+3b/b-a=?
a=8b
(4a+3b)/(b-a)=
=(4*8b+3b)/(b-8b)=
=(32b+3b)(-7b)=
=35b/(-7b)=
=35/(-7)=-5