Question

3 si 4
Dau coroana si 28 de puncte.
Materie clasa a 10-a.
Multumesc anticipat.​

Answer 1

Răspuns:

Explicație pas cu pas:

4^x - 2^x = 12

2^2x - 2^x = 12

2^x = y

y^2 - y = 12

y^2 - y - 12 = 0

Δ = 1 + 48 = 49

y1 = (1 + 7)/2 = 8/2 = 4

y2 = (1 - 7)/2 = -6/2 = -3

2^x > 0

2^x = 4 = 2^2

x = 2

__________________________

A = {1, 2, 3, 4, 5, 6}

AxA = {(1, 1); (1, 2); (1; 3); (1, 4); (1, 5); (1, 6); (2, 1); (2, 2); (2,3); (2,4); (2,5); (2,6); (3,1); (3,2); (3,3); (3,4); (3,5); (3,6); (4,1); (4,2); (4,3); (4,4); (4,5); (4,6); (5,1); (5,2); (5,3); (5,4); (5,5); (5,6); (6,1); (6,2); (6,3); (6,4); (6,5); (6,6)}

total elemente = 36

elemente cu produsul a x b impar = 9

P = 9/36 = 1/4