54÷27=2
2×4=8(девочки)
54÷18=3
3×5=15(мальчики)
54-(8+15)=54-23=31роликов осталось
Используя a²-b²=(a-b)(a+b)
домножаем числитель и знаменатель на 9²-5²=(9-5)(9+5)= 4 * 14 = 56
(9²-5²) * (9²+5²)(9⁴+5⁴)(9⁸+5⁸)(9¹⁶+5¹⁶)(9³²+5³²)(9⁶⁴+5⁶⁴) / (9²-5²) =
(9⁴-5⁴) * (9⁴+5⁴)(9⁸+5⁸)(9¹⁶+5¹⁶)(9³²+5³²)(9⁶⁴+5⁶⁴) / 56 =
(9⁴-5⁴) * (9⁴+5⁴)(9⁸+5⁸)(9¹⁶+5¹⁶)(9³²+5³²)(9⁶⁴+5⁶⁴) / 56 =
(9⁸-5⁸) * (9⁸+5⁸)(9¹⁶+5¹⁶)(9³²+5³²)(9⁶⁴+5⁶⁴) / 56 =
(9¹⁶-5¹⁶) * (9¹⁶+5¹⁶)(9³²+5³²)(9⁶⁴+5⁶⁴) / 56 =
(9³²-5³²) * (9³²+5³²)(9⁶⁴+5⁶⁴) / 56 = (9⁶⁴-5⁶⁴) * (9⁶⁴+5⁶⁴) / 56 =
(9¹²⁸-5¹²⁸) / 56 как то так
<span>7 1/2=7,5 и 17 21/84=17,25</span>
A∈[825;827]
///////////////////
A) 0,36 = 36/100 = 9/25
б) 0,7 = 7/10
в) 0,625 = 625/1000 = 5/8<span>
</span>