5) все приводим в числу и по правилу вычисляем
6a-3a^2-a^2+4a-4=-4a^2+10a-4
25-12x+(x-5)*(x+5)-(5-x)²=25-12x+(x-5)*(x+5)-(x-5)²=
=25-12x+(x-5)*(x+5-x+5)=25-12x+(x-5)*10=25-12x+10x-50=
=-2x-25=-(2x+25).
81 ;-81 ;81.....64; -64 ;64
36; -36 ;36.....27; -27 ;27
9)2.1/(6.6-2.4)=2.1/4.2=0.5
10)7.2/(8.3-8.6)=-7.2/0.3=-24
11) 9.2/(0.5-2.8)=-9.2/2.3=-4
12)9.4/(4.1+5.3)=9.4/9.4=1
13)(9.5+8.9)/2.3=18.4/2.3=8
14)(6.8-4.7)/1.4=2.1/1.4=1.5
15)(1.7+3.8)/2.2=5.5/2.2=2.5
16)(7.2-6.1)/2.2=1.1/2.2=0.5