3/18+2/3=3/18+12/18=15/18=5/6
6/15+7/20=24/60+21/60=45/60=3/4
1/12+3/4=1/12 +9/12=10/12=5/6
6/14+7/21=18/42+14/42=32/42=16/21
2/45+5/9=2/45+25/45=27/45=3/5
4/21+6/28=16/84+18/84=34/84=17/42
1/42+2/14=1/42+6/42=7/42=1/6
<span>8/18+6/27=4/9+2/9=6/9=2/3</span>
2928-88=2840
2840:142=20
_____________
64+37+101
101·91=9191
S AB=5см*5см*3,14=78,5см^2
<span>S OD=10см-2см=8см(диаметр ОD)=>r=4см;=>S OD=4см*4см*3,14=50,24см^2</span>
Я тебе решила 1 и 2 задание, 1 варианта
Ответ:
ab-4b-ac+4c= a(b-c)-4(b-c)=(a-4)(b-c)
(a-c)(a+c)-(a-2c)²= a²-c²-a²+4ac-4c²=4ac-5c²=c(4a-5c)
3а-аy+by-3b= 3(a-b)-y(a-b)=(3-y)(a-b)
(a+2b)(a-2b)-(a-b)²= a²-4b²-a²+2ab-b²=2ab-5b²=b(2a-5b)