Question

Soluţia ecuaţiei log2 (x2 + 3⋅ x −10) = 3

Answer 1

CE x²+3x-10 > 0, delta = 9+40 = 49

x1 = (-3+7)/2 = 4/2 = 2 >0 adevarat

x2 = (-3-7)/2 = -10/2 = -5 >0 fals

deci x apartine (2,infinit)

Folosesti formula loga (b) = c  de unde b = a^c

x² +3x-10  =2³

x²+3x-10-8=0

x²+3x-18=0

delta = 9+72 = 81

x1 = (-3+9)/2 = 6/2 = 3 apartine (2,infinit)

x2 = (-3-9)/2 = -12/2 = -6 nu apartine (2,infinit)

Deci S={3}