3) 3/10
4) 4/14
5) 4/5
6) 4/15
7) 26,3
8) 4,5
9) 19,68
10) 1,6
Объяснение:
3) (6/5-3/4) * 2/3 = ((24-15)/20) * 2/3 = 9/20 * 2/3 = 3/10
4) (8/7-1/14+1/42) * 12/46 = ((48-3+1)/42) * 12/46 = 46/42 * 12/46 = 12/42 = 4/14
5) 1 2/5 + 3/8 - 39/40 = 7/5 + 3/8 - 39/40 = (56 + 15 -39)/40 = 32/40 = 4/5
6) (6/5 - 2/3) * 1/2 = ((18-10)/15) * 1/2 = 8/15 * 1/2 = 4/15
7) 6,8 * 3,5 + 2,5 = 23,8 + 2,5 = 26,3
8) 8,26 - 7,52 : 2 = 8,26 - 3,76 = 4,5
9) 4,6 * 3,9 + 1,74 = 17,94 + 1,74 = 19,68
10) 4,51 - 5,82 : 2 = 4,51 - 2,91 = 1,6
В 4) и 5) дроби сокращены.
216x^3 - 1 = (6x)^3 - 1^3 = (6x-1)(36x^2+6x+1)
100b^2 - 140bx^2 + 49x^4 = (10b - 7x^2)^2=(10b-7x^2)(10b-7x^2)
125b^3 + 27 = (5b + 3)(25b^2 - 15b + 9)
(5a - 1/5)^2 = 25a^2 - 2a + 1/25)
(3a - 5b^2)(9a^2 + 15ab^2 + 25b^4) = (3a)^3 - (5b^2)^3 = 27a^3 - 125b^6
(0,8x+ 5)(5 - 0,8x) = (5 + 0,8x)(5 - 0,8x) = 5^2 - (0,8x)^2 = 25 - 0,64x^2
(7x+ 0,4)^2 = 49x^2 + 5,6x + 0,16
(6y + 1)(36y^2 - 6y + 1) = (6y)^3 + 1^3 = 216y^3 + 1
25x^2 + 60xy + 36y^2 = (5x + 6y)^2 = (5x + 6y)(5x + 6y).