2+3=5,3+2=5,8-3=5,9-4=5,4+4=8,5+3=8,10-2=8,13-5=8,4+3=7,3+4=7,14-7=7,11-4=7,4+2=6,3+3=6,12-6=6,21-15=6
AA1B1B-сечение
ОА=ОВ=6√2
<AOB=120
<A1BA=60⇒<AA1B=30⇒AB=1/2A1B
AB²=OA²+OB²-2OA*OB*cos120=OA²+OB²+2OA*OB*cos60=72+72+2*72*1/2=216
AB=6√6⇒A1B=12√6
AA1=√A1B²-AB²=√144*6-36*6=√108*6=√36*18=√36*9*2=6*3√2=18√2
S=AA1*AB=18√2*6√6=108√12=108*2√3=216√3см²
1)5х+6=12.5х
5х-12.5х=-6
х=-1.25
2)12-8х+24=6+4х
-8х-4х=6-12-24
-12х=-30
х=-2.5