Question

Cum se face ???????♡♡

2x (1+2+3+.......+2013)-2013 este patratperfect   

Care sunt nr ab (cu bara deasupra) in baza 10 stiind ca ab (cu bara deasupra=ba (cu bara deasupra)+18????♥♡♥♡

Answer 1

2 × ( 1 + 2 + 3 +...+ 2013) - 2013 =

2 × 2013 × 2014 : 2 - 2013 =

2013 × 2014 - 2013 =

2013 × (2014 - 1) =

2013 × 2013 =

2013^2 este patrat perfect



ab = ba + 18
10a + b = 10b + a + 18
9a = 9b + 18 |:9
a = b + 2

a si b diferite de 0

3 = 1 + 2 => a = 3 si b = 1
4 = 2 + 2 => a = 4 si b = 2
5 = 3 + 2 => a = 5 si b = 3
6 = 4 + 2 => a = 6 si b = 4
7 = 5 + 2 => a = 7 si b = 5
8 = 6 + 2 => a = 8 si b = 6
9 = 7 + 2 => a = 9 si b = 7

ab = 31; 42; 53; 64; 75; 86; 97


facem verificarea:

31 = 13 + 18
42 = 24 + 18
53 = 35 + 18
64 = 46 + 18
75 = 57 + 18
86 = 68 + 18
97 = 79 + 18