Question

2. Să se determine x număr natural dacă:
x:3, x<20
(x+1):4, x≤ 15
e) (2x-3): 7, x< 15
22. Să se demonstreze
c) (x-2):6, x<25
g) 9 (4x-1), x<20
f) 2 (2x+5)
că oricare ar fi cifrele a, b:
12hg 120):11
d) (2x+1)::
c) (ah7-4ab):3 va rogg repedeeee coroana

Answer 1

Explicație pas cu pas:

x:3, x<20

=> x ∈ {0, 3, 6, 9, 12, 15, 18}

(x+1) : 4, x ≤ 15

=> x ∈ {3, 7, 11, 15}

c)

(x-2) : 6, x<25

0 ≤ x < 25 <=> -2 ≤ x-2 < 23

(x-2) : 6 => (x-2) ∈ {0, 6, 12, 18} |+2

=> x ∈ {2, 8, 14, 20}

e)

(2x-3) : 7, x < 15

0 ≤ x < 15

0 ≤ 2x < 30

-3 ≤ 2x-3 < 27

=> (2x-3) ∈ {0, 7, 14, 21} |+3

2x ∈ {3, 10, 17, 24}

x∈ℕ => 2x ∈ {10, 24}

=> x ∈ {5, 12}